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Fifth Grade - Science - Overview - January

This month in science, students study the cell. After Lesson 24, they should be familiar with the basic parts of a typical cell, and this knowledge is expanded in Lessons 25 and 26 to include cells without nuclei and structures found in plant cells. Students are prompted to think about how cell function influences cell shape, and identify organisms that consist of only a single cell. An important part of this unit is the experiment which students conduct on bacterial growth; through this activity students are introduced to the scientific method. Finally, subjects covered in Lessons 27 and 28 include cell division and organization and the work of Ernest Just.

Most of the lessons in January include websites that students can use to obtain further information and to enhance their study of the cell. Many of the websites noted were found through links provided by the Biodiversity and Biological Collections Web Server, which in itself contains much information pertinent to the unit on cells, though some of it is above the fifth grade level. This website can be found at http://muse.bio.cornell.edu/.

You may also wish to inform students and their families that related to this science unit, the Maryland Science Center is offering a weekend workshop entitled "Biology: Living World" for fourth and fifth graders. This workshop is being offered as a part of the PRISM Program, and further information about it can be obtained by calling the PRISM Program Coordinator at 410-545-5951, or by writing the Education Department at the Maryland Science Center, 601 Light Street, Baltimore, MD 21230.

If you plan to use the assessment provided for this month, tell students to carefully store all of the handouts they receive over the course of the unit. They will need to use them to study for this test, as it contains much content. You will also want to assign study of the materials on these sheets for homework, and may wish to review with students good study skills. It would be best for students if they were told to begin to study each of the handouts as it is received instead of trying to "cram" just prior to the administration of the assessment.
 

Fifth Grade - Science - Lesson 24 - The Structure of Cells
 

Objectives

Recognize that all living things are made up of cells.

Construct a cell model.

Draw and label the parts of a cell.

Begin a K-W-L chart.
 

Materials

For each group:

One individual, disposable aluminum muffin cup, about three quarters full of light- colored Jell-O or a gelatin and water mix

One piece of jaw breaker candy

Two grapes

Two jelly beans

For each student:

One copy of "The Cell" worksheet (attached)

Chart paper or a transparency sheet and overhead projector

Transparency or classroom-size drawing of a cell (attached)

Crayons or markers for small groups of students to share
 

Suggested Books

Student Reference

Bender, Lionel. Atoms and Cells. New York: Gloucester Press, 1990. On pages 16-17 of this text are large, colorful photos of magnified cells and a drawing of a cross-section of a cell with its parts labeled.

Cole, Joanna. The Magic School Bus Inside the Human Body. New York: Scholastic Inc., 1989. Though this book is directed more towards the primary grades, it would serve as a good reminder of content covered in the Second Grade.

Fichter, George. Cells. New York: Franklin Watts, 1986. This book contains excellent diagrams of plant and animal cells on pages 16 and 18. Chapter two, "A Typical Cell," is pertinent to today's lesson, but the reading level may be difficult for some fifth graders.

Young, John K. Cells. New York: Franklin Watts, 1990. Detailed descriptions of the parts of a typical cell are given as a part of chapter three of this book.
 

Teacher Resource

Grambo, Gregory, Dean Medley and Kelly Medley. "Life is a 'Cell-ebration!'" The Mailbox. October/November 1995, 37-43. This article contains suggestions for good hands-on activities for cell exploration.

Hirsch, E.D. What Your Fifth Grader Needs to Know. New York: Doubleday, 1993. Excellent background information for today's lesson is contained within this book.
 

Website

http:/www.cellsalive.com/howbig.htm This website shows the size of various cells by comparing drawings of them to a bar representing 0.01mm.
 

Teacher Background
 

In this lesson, students are first reminded that all living things are made up of cells and briefly review what they remember about cells from Second Grade. Students then make a model of a cell within cooperative groups, and are introduced to various parts of a typical cell. Once this has been done, students are asked to individually diagram a cell and label its parts.

In Second Grade, students learned that cells are tiny living organisms that make up our bodies. They should remember that the only way to see cells is through a microscope. They may also remember that cells from different parts of the body may look different from one another, as cells are designed to do different jobs. Students were also taught that our bodies continue to make new cells to replace old ones throughout our lives, and that Anton von Leeuwenhoek developed the microscope and became the first person to correctly describe red blood cells.
 

Procedure

Tell students that this month they will continue to study life, though instead of classification, they will be examining the tiny components that make up all living beings. Have them think back to Second Grade and ask: Does anyone remember what the tiny parts of every living thing are called? (cells)

On chart paper or the overhead, begin a K-W-L chart by asking students first what they know already about cells and listing this information under the K (for "know"). Then, ask students what they would like to know about cells and list their questions under the W (for "want to know").

Tell students that perhaps some of their questions will be answered today, as they will be building a model of a typical cell. Organize students into groups of about four or five, then pass out the group materials. On the overhead or on chart paper, display the drawing of the cell that is attached. Tell students that cells are made up of parts that are called organelles. Each organelle has a specific job to do for the cell, and as they are building the cell models, they will be learning about the organelles.

First, have students look at the muffin cup that is almost full of Jell-O. Explain that for the purposes of this class, they should consider the muffin cup and its contents a cross-section of a cell. Tell them that the cup itself represents the cell membrane, and point it out on the drawing. The membrane completely surrounds the cell and has the job of controlling what goes in and out of the cell. The membrane has small openings that allow it to do this job. Ask: How is the cup unlike the cell membrane? (It does not completely surround what is inside of it, it is not permeable.) Can you think of another object which would be a better representation of the cell membrane? (Answers will vary, but may include ideas and objects such as two colanders taped together, a whiffle ball, etc.)

Next, have students observe the material inside the muffin cup. Ask: How would you describe this material? (half liquid and half solid, jelly-like, etc.) Tell students that cells are indeed filled with a substance much like this. Point out the label of cytoplasm on the drawing and tell the students that this is the name of the substance. Explain that cytoplasm is where most of the chemical processes take place within the cell.

Ask students to next take the jawbreaker from the other materials. Ask students if they have ever observed a jaw breaker after biting it, or have taken it from their mouths after sucking on it for a while. What did they notice? (The jawbreaker has various layers which are frequently different colors.) Tell students that the nuclear membrane and nucleus are almost like a jawbreaker. The nuclear membrane surrounds the nucleus like an outside layer of a jawbreaker, and the job of the nuclear membrane is to control what goes in and out of the nucleus. The nucleus, which would then be like the center of the jawbreaker, is inside the nuclear membrane. The nucleus is the control center for the cell. It is here that the most important cell information is stored, and the nucleus is what directs the activities for the cell. Have students push the jawbreaker into the Jell-O so that now their cell models have a cell membrane, cytoplasm, and a nucleus surrounded by a nuclear membrane. Ask: Now that you see the function and location of the cell membrane and nuclear membrane, what conclusions can you draw about membranes? (They surround other things and control what goes in and out of them.)

Next, have students take the grapes from the other materials, and ask them to describe the structure of the grapes. (They have a very thin skin, and are filled with a gelatinous substance.) Tell students that in their model, the grapes are going to represent the vacuoles (point out on the diagram). Students should place the grapes into the Jell-O in the muffin cup. Explain that in the typical cell, vacuoles are oval structures, like grapes, and that inside of them the cell stores food, water or wastes. The vacuoles are therefore similar to storage bins, or cabinets, for the cell. Ask: How is the structure of the grape similar to the structure of the vacuole? (Both have an outer layer that surrounds something being held on the inside.)

The final organelles that students will be learning about today are the mitochondria. Have students take out the jellybeans and tell them that the mitochondria are shaped like kidney beans, just as the jellybeans are. The mitochondria have the job of changing food into energy the cell can use to do its work. Students should place the mitochondria into the Jell-O as well.

Tell students that though some cells have additional parts to do specific jobs, all typical plant and animal cells have these features. Plant and animal cells may also be shaped differently, and they will be learning more about this in the next lesson. Ask: Which of the organelles do you think is the most important to the cell? Why? (Answers will vary, but it is expected that most students will come to the conclusion that the nucleus is, since it controls the cell's activity.) What other substance could be used to represent the cytoplasm in the model? (Answers will vary, but may include jelly, mayonnaise, etc.) Remind students that the mitochondria help change food into energy for the cell. Ask: What part of your body does the same thing for you? (It is expected that students will say the stomach, but any part of the digestive system would be an acceptable answer.) If the cell needed some food turned into energy, where might it tell its mitochondria to go to get some food that has been stored? (the vacuoles) What part of the model do you think is the best representation of the actual organelle? Why? (Answers will vary.)

Tell students that they will now be drawing their own picture of a typical cell. Pass out "The Cell" worksheets and the crayons or markers. Instruct the students to now draw the typical cell in the frame provided and to label its parts, which are listed below the frame and should be spelled correctly by the students. Next to each label, students should try to remember a fact about the job or function of the organelle, and write it in a few words or a phrase, for example, "cell membrane--controls what goes in the cell." (If there is not room for this information next to the label, students may write it next to the organelle name on the bottom of the worksheet.) Encourage students to look at their cell models to trigger mental clues if they need help remembering the function of any of the organelles. Tell students that the labeling should be done in pencil so that it can be corrected if necessary, and that the location of the organelles within the cell does not matter.

When students have finished, ask for volunteers to point out the organelles on their drawings and to tell the function that they remembered for each (if any were missed by students, they should be added or corrected now). These functions are listed below:
cell membrane: controls what goes into and out of the cell
cytoplasm: where chemical processes take place
nuclear membrane: controls what goes in and out of the nucleus
nucleus: stores important information and controls activities
vacuoles: store food, water or waste
mitochondria: change food into energy
Congratulate students who were able to remember the functions of most of the organelles, and praise all the students for trying.

Finally, explain the history of the name "cell." Ask: If you were told that the word "cell" is a scientific name that was given over 300 years ago, in the 1600s, what language would you assume it to be? If necessary, tell students that it is the same language that is used in animal classification. (Latin) The name "cell" was given by an English scientist, Robert Hooke, while looking at some thin slices of cork through his microscope. He noticed a pattern of small, boxlike squares in the cork, that to him looked like tiny rooms. The Latin word for room is "cella," so he called these small structures "cells." Tell students that they will be learning even more about cells in the next lesson.

Suggested Follow-up Activities

If you have access to a microscope, there are a number of activities you can do to enrich students' learning about cells. One that is commonly done allows students to see cells from the human body. Ask the students to gently scrape the inside of their cheek with a toothpick, then to stir the end of the toothpick into a drop of water on a slide. A drop of iodine should then be added to the mixture on the slide, and a slide cover placed on top. The slide may then be viewed under the microscope, and after careful focusing, students should be able to see their own cells.
Since students have a list of the organelles and their functions, you may wish to quiz them on this content in the next lesson.
 

Fifth Grade - Science - Lesson 25 - Functional Cell Shapes and Plant Cells

Objectives

Design cell shapes based on a given function and justify the designs in writing.

Compare and contrast the student-made designs to the actual cell shapes.

Develop similes comparing cells and cell structures to other things.

Identify two structures found in plant cells not found in animal cells.
 

Materials

One copy for each student of the cell shape worksheet (attached)

Transparency or diagram on chart paper of plant and animal cells (attached)

One copy for each student of the cell simile worksheet (attached)
 

Suggested Books

Student Reference

Bender, Lionel. Atoms and Cells. New York: Gloucester Press, 1990. On pages 16-17 of this text are large, colorful photos of magnified cells and a drawing of a cross-section of a cell with its parts labeled. Additionally, on pages 18 and 19 are diagrams of cross-sections of plant cells, with the cell wall and chloroplast labeled.

Cole, Joanna. The Magic School Bus Inside the Human Body. New York: Scholastic Inc., 1989. Pertinent to this lesson, in this book there are diagrams of lung, muscle and brain cells and a discussion and description of red and white blood cells.

Fichter, George. Cells. New York: Franklin Watts, 1986. This book contains excellent diagrams of plant and animal cells on pages 16 and 18, and on page 19 is a diagram of photosynthesis taking place within a plant cell. Chapter three, "Your Body's Special Cells," is pertinent to today's lesson and contains photographs of nerve and red blood cells, but the reading level may be difficult for some fifth graders.

Young, John K. Cells. New York: Franklin Watts, 1990. Different types of cells within the human body are described as a part of chapter two of this book.
 

Teacher Resource

Grambo, Gregory, Dean Medley and Kelly Medley. "Life is a 'Cell-ebration!'" The Mailbox. October/November 1995, 37-43. This article contains suggestions for good hands-on activities for cell exploration.

Hirsch, E.D. What Your Fifth Grader Needs to Know. New York: Doubleday, 1993. Excellent background information for today's lesson is contained within this book.
 

Website

http://www.cellsalive.com/ This website is a wonderful resource for information on cells. Pertinent to this lesson, there are photographs and drawings of cells that clearly show their shape and movement.
 

Teacher Background

In this lesson, students are asked to think about the functions that different cells serve. Based on a given function, they are asked to design shapes for cells, then to justify their designs. Once this has been done, students see the way that these cells are actually shaped, and compare and contrast their own designs to those found in nature. Students then learn about the two structures found in plant cells that are not found in animal cells: the cell wall and chloroplasts.

Students end the lesson by writing similes comparing cells and cell structures to other objects, and explaining their comparisons.

Students were taught in Kindergarten that one of the main differences between animals and plants is that plants make their own food. They also should know that plants need sunlight in order to do this. As a part of the Second Grade Science curriculum, students were told that cells from one part of the body may look different that cells from another part of the body, and the examples of muscle, nerve and nasal cells were used to briefly explain this. In the Fourth Grade, students were taught limited information about red and white blood cells within a study of the circulatory system.
 

Procedure

Begin today's lesson by telling students that in the last lesson, they learned about the organelles that most cells have in common, but in today's lesson, they will learn about some of the differences that exist among cells. As they learned in the last lesson, each of the organelles has a specific job to do. Like the organelles, each cell also has a job to do. Cells are shaped differently to perform their jobs well.

Discuss with students the idea that the function or purpose of an object can greatly influence its shape. For example, a rocket has the job of moving quickly through the air. Its long and narrow shape allows it to perform this function well. If it were wide at the top, it would not be aerodynamic enough to achieve this goal. Another example of form following function is the bathtub. It is big enough to hold water and allow the person bathing to sit comfortably, but is shaped so that water will reach a comfortable depth quickly. If it were much wider, water would be wasted, and if it were in the shape of a small circle, people would not be able to maneuver around in it adequately enough to bathe. Make sure students understand that the shape of these items is dictated by the individual item's intended use, and ask if they can think of further examples.

Tell students that cell shapes are also influenced by the jobs they need to do. Pass out copies of the "Cell Shape Worksheet." Explain to students that they need to think about the purpose of the cell, then think about how the cell could be shaped to allow it to perform this job well. Should the cell be very long and narrow, wide and flat, or perhaps round? Once they have decided what shape they think the cell should be in order to perform its function well, they should draw the cell shape in the box provided. Students do not need to draw and label the organelles within each cell, just the shape of the cell needs to be depicted. Once this has been done, they should explain in writing their reasoning for shaping the cell the way that they did. So that students clearly understand this task, you may want to do the first one together. Emphasize that there is not a wrong or right answer to the question of cell shape. Every answer is legitimate as long as the explanation, or justification, of the shape makes sense.

Once students have completed their proposed cell shapes and have justified each drawing, tell them that they will now find out how each of these cells are actually shaped. Begin with the muscle cell, and ask for students to share their thoughts on how this cell should be shaped to perform the job of expanding and contracting. To further their understanding of this function, have them gently place their left fingers on their right biceps, with their right arms extended. Keeping their fingers in place, have students bend their right arms at the elbow and "make a muscle." They should be able to feel that the biceps muscle cells in their arms have gone from long and thin, when arms were extended, to short and thick when they made a muscle. Tell them that in reality, a muscle cell is long and thin, like a pencil, so that it can contract. Ask: Did anyone draw the muscle cell as long and thin? How were other drawings different than or similar to the real shape of a muscle cell?

Then, move on to the red blood cell. Again, have students show the shape they drew and read their justification. Tell students that the red blood cell is actually round and has an indentation in the middle. It looks somewhat like a doughnut that has not had the middle totally cut out. This type of cell is also very tiny. Its small, round shape allows it to do the squeezing necessary for it to function well. Ask: Who drew the shape of the red blood cell as tiny, for squeezing purposes? How else were predicted shapes similar to the real shape of a red blood cell? How might the round edges of a red blood cell allow it to squeeze in and out of blood vessels? Who thinks their designed shape would work even better than the actual one? Why?

Third is the tree trunk cell. Students should again share their shapes and justifications. Then, tell them that in reality, a tree trunk cell is long and thin and forms a tube, like a straw, to transport the food and water up and down the tree. Ask: Why does this shape make sense for this function? Whose drawn shape is the most similar to the actual shape of a tree trunk cell? Whose drawn shape is most unlike the actual shape of a tree trunk cell? How might this dissimilar shape work even better than the actual shape for the purpose described of moving food and water?

Finally, ask for students to share their ideas about how they think the plant leaf cell should be shaped. Tell them that the plant leaf cell is flat and wide. This increases its surface area and allows it to catch the maximum amount of sunlight. So that students understand this concept, have them cup one hand so that it is almost in a fist. If it were snowing, think about how many flakes would land on your hand with it in this position. Then, tell students to extend their fingers out flat. Ask: Would more snowflakes land on their hand in this position? (yes) Why? (With fingers out flat, there is a greater surface on which snowflakes can land.) So that it can catch the more of the sun's rays, each plant leaf cell is shaped like their hands were in the second position. Ask: Would it be more important for the cell to be flat or wide in order to increase surface area? Why? (wide, because flat could also be very narrow and small, and would not allow for very many rays to be captured--even if the cell were rounded, if it were wide, much of its surface would be exposed to the rays) Were there any predicted shapes that were wide? Were there any that were flat? How could you combine the wide and flat properties with your design to make the "ultimate" ray-catching cell?

Tell students that thinking about the differences between cell shapes can prompt them then to think about the differences between the structures within plant and animal cells as well. Ask: What are some basic differences between plants and animals? (Accept all reasonable answers, but when a student volunteers that plants make their own food and animals do not, end the discussion.) Tell students that this difference, that plant cells make their own food, results in plant cells having two parts that animal cells do not. These parts are in addition to the organelles studied in the last lesson, which almost every plant and animal cell has. Instruct students to listen, as these parts are being discussed, and to think about what these parts could be compared to.

Display the transparency or illustration on chart paper of the plant and animal cells. Ask: Who notices something very close to the cell membrane of the plant cell which is not present in the animal cell? (the cell wall) Tell students that the cell wall is a sturdy layer around the outside of the cell which gives the cell a rigid shape. In addition to supporting the shape of the plant cell in this way, the cell wall protects the soft inside of the plant cell.

Ask: Who sees the other type of structure that the plant cell has that the animal cell does not have? What is it? (the chloroplast [KLOR-uh-plast]) Tell students that the chloroplasts within a plant cell contain the substance that allows the plant to make its own food, the chlorophyll (KLOR-uh-fill). The chlorophyll is what captures the sunlight and enables the plant to change it into energy.

So, the plant cell has two types of structures the animal cell does not have: the cell wall and chloroplast. Within each chloroplast is a substance that the animal cell also does not have, chlorophyll.

Tell students that you hope they were thinking about what these parts could be compared to and pass out copies of the "Cell Simile Worksheet." If necessary, remind students that a simile is a comparison of one thing to another using the word "like" or "as." Point out that the worksheet asks them to compare the cells and cell structures they learned about to other items, and tell them that one way these comparisons could be done is to base them on the function of the cell or cell structure. (For example, one could write that the chloroplasts are like filled grocery bags because they contain the substance that allows the plant to make its own food.) For the cells, the comparisons could also be based on the cell shape. (For example, the tree trunk cell is like a straw because it is long and thin.) When they are thinking about items to use in the comparisons, encourage students to think creatively. Not only can items such as a straw or grocery bag be used, but students can also compare the cell or cell structure to an occupation. (For example, one could write that the cell wall is like a guard because it controls what goes in and out of the cell.) Students can use the cell functions that are described under Cell Type on the "Cell Shape Worksheet" to help them think of comparisons.

Allow adequate work time for students to fill in the worksheet, and when they are finished, ask them to share their comparisons and explanations. As you collect the cell simile worksheet and the cell shape worksheet for grading purposes, congratulate students on their creative answers and clear justifications. Tell them that in the next lesson, they will be beginning an experiment on cell growth.
 

Suggested Follow-up Activities

It is hoped that as the lessons is this unit are completed, some of the questions about cells, generated as a part of the K-W-L chart begun in Lesson 24, will be answered. As a follow-up to this lesson, you may wish to have students research the answers to questions not yet answered and either share their information in an informal presentation, or when the topic comes up in the following classes in this unit.
 

Students may enjoy doing further research on the shapes of various cells. If this is done, they could draw each cell shape they learn about and write a brief explanation of the cell's purpose. The shapes and purposes could be separated and displayed on a bulletin board, with a challenge for students to correctly match each shape to a described cell purpose.
 

A variation to the activity above involves having students describe a cell's purpose without giving away what type of cell it is, and along side of this description draw the cell's shape. The shapes and their accompanying descriptions would be displayed, and those viewing the display would be challenged to try to figure out what type of cell each is, based on the information provided. The name of the cell, for example, nerve cell, would be written on a sheet of paper tucked behind the picture so that those guessing can check their guess. (See illustration below.)
 

Fifth Grade - Science - Lesson 25 - Functional Cell Shapes and Plant Cells
 

CELL SHAPE WORKSHEET Name______________________
CELL TYPE
SHAPE
JUSTIFICATION
Muscle Cell

Must be able to expand and contract (grow longer and shorter) in order to make the body move

____________________ 
 

____________________ 
 

____________________ 
 

____________________

Red Blood Cell

Must be able to squeeze through blood vessels to bring oxygen to other cells of the body

____________________ 
 

____________________ 
 

____________________ 
 

____________________

Tree Trunk Cell

Must be able to transport food and water up and down the tree 
 

____________________ 
 

____________________ 
 

____________________ 
 

____________________

Plant Leaf Cell

Must be able to catch the maximum amount of sunlight for the plant to use to make food

____________________ 
 

____________________ 
 

____________________ 
 

____________________


 

Cell Simile Worksheet
 

Name___________________________________________
 

Directions: Complete each simile by thinking of a comparison for the cell or cell structure given, and explain your choice.
 

1. The muscle cell is like ____________________ because __________________________________________________

2. The red blood cell is like ____________________ because

__________________________________________________

3. The tree trunk cell is like ____________________ because

__________________________________________________

4. The plant leaf cell is like ____________________ because

__________________________________________________

5. The cell wall is like ____________________ because

__________________________________________________

6. The chloroplasts are like ____________________ because

__________________________________________________

7. The chlorophyll is like ____________________ because

__________________________________________________

Fifth Grade - Science - Lesson 26 - Surprising Cell Facts and the Scientific Method

Bacteria experiment adapted from Accent on Science, by Dr. Robert B. Sund, Dr. Donald K. Adams and Dr. Jay K. Hackett, page 51.
 

Objectives

Recognize that monerans are an exception to the regular cell structure model.

Identify organisms that consist of a single cell.

Read the five steps of the scientific method.

Complete the first two steps, and begin the third, in an experiment on the growth of bacteria.

Compose a question that will be answered by the experiment.

State a hypothesis to answer the composed question.

Construct the set up for the experiment.
 

Materials

One copy for each student of the Scientific Method worksheet (attached)

For each group: four clear plastic cups

approximately 2 cups of a mixture of bouillon and water

one tablespoon each of: salt; sugar; baking soda; bleach

four pieces of masking tape, each approximately 2" long

one copy of the Bacteria Experiment Worksheet (attached)

one copy of the attached data collection chart (if possible, copied on the back side of the Bacteria Experiment Worksheet)
 

Suggested Books

Student Reference

Bender, Lionel. Atoms and Cells. New York: Gloucester Press, 1990. Information about amoeba, bacteria and algae is contained in this text, and there are fabulous photographs and diagrams of these organisms as well.

Berger, Melvin. Germs Make Me Sick. New York: HarperCollins, 1985. Though this book is written with younger students in mind, it does do an excellent job of explaining the relationship between bacteria and illness.

Bleifeld, Maurice. Experimenting with a Microscope. New York: Franklin Watts, 1988. The history and parts of a microscope are detailed in this book, and the subjects covered in today's lesson are covered as well. The diagrams and experiment suggestions make this a practical book for the classroom with access to a microscope.

Coldrey, Jennifer. Discovering Fungi. New York: The Bookwright Press, 1988. The photographs and easy reading style of this book would make it appealing to fifth graders.

Cosgrove, Margaret. Wonders Under a Microscope. New York: Dodd, Mead and Company, 1959. The history and use of a microscope are contained within this book, and it describes various experiments and investigations that can be undertaken with a microscope. Subjects discussed in today's lesson are also addressed.

Froman, Robert. Mushrooms and Molds. New York: Thomas Y. Crowell Company, 1972. Though this book is written for younger readers, it describes these organisms well, and gives suggestions for activities students could easily do at home to further observe mushrooms and mold.

Villiard, Paul. The Hidden World: The Story of Microscopic Life. New York: Four Winds Press, 1975. There are some great photographs in this book of organisms that can only be seen under a microscope. This text also briefly discusses the organisms studied in today's lesson.

Young, John K. Cells. New York: Franklin Watts, 1990. Monerans (bacteria) are discussed in several places in this book.
 

Teacher Resource

Dashefsky, H. Steven Microbiology: 49 Science Fair Projects. New York: TAB Books, 1994. The scientific method is described on pages 14-16.

Hirsch, E.D. What Your Fifth Grader Needs to Know. New York: Doubleday, 1993. Excellent background material for today's lesson can be found within this book.

Lammert, John M. Science Fair--How to do a Successful Project: Microbes. Vero Beach, FL: Rourke Publications, Inc., 1992. The scientific method is described on pages 4-7.

Sund, Dr. Robert B., Dr. Donald K. Adams and Dr. Jay K. Hackett. Accent on Science. Columbus, OH: Charles E. Merrill Publishing Co., 1982. This text describes and has pictures of the microorganisms studied in today's lesson.
 

Websites

http://commtechlab.msu.edu/sites/dlc-me/ This is the website for the Digital Learning Center for Microbial Ecology. It contains a wealth of information, much of it at an appropriate level for fifth graders, about the cells being studied as a part of this lesson. Particularly, there are photos of present and past "Microbes of the Week," complete with their scientific classification information, as well as a subsite called "The Microbe Zoo," which gives images and descriptions of microscopic organisms and the habitats, such as a pond, where they live. "The Microbe Zoo" is also available on CD-ROM.

http://www.cellsalive.com/ Much information about bacteria is contained within this website. Among other things, the writers describe and illustrate with photographs bacterial mobility and growth.

http://www.herb.lsa.umich.edu/kidpage/factindx.htm This is part of the Fun Facts Catalog sponsored by the University of Michigan. This website, "Fun Facts About Fungi," has lots of graphics and would be found appealing by any fifth grader doing further research about fungi.

http://www.perspective.com/nature/fungi/ Though the reading level may be difficult for some fifth graders, this website does a terrific job of describing the role of fungi in nature. Related to both this lesson and the previous unit, it details the scientific classification of various types of fungi and what this classification is based on.
 

Teacher Background

In today's lesson, students will learn about an exception to the typical cell, monerans, which are bacteria without nuclei. They will also hear about some tiny microorganisms that consist of only a single cell. The knowledge they acquire today should help them to more fully understand the division of living things into kingdoms, which was studied last month.

Students will also be introduced to the scientific method in this lesson and will begin an experiment on bacterial growth. (If the given vocabulary regarding the scientific method differs from one your students are more familiar with, you may wish to alter the worksheet accordingly.)

The bacteria will be growing in the plastic cups, each of which will contain a water and bouillon mixture and one other substance. Students will hypothesize about which cup will produce the most bacteria the fastest, and will record observations in the days between this lesson and the last lesson of this unit. During the last lesson, they will analyze the results of the experiment and draw conclusions based on the results.

It is extremely important that students understand that some of the substances used during this experiment can be dangerous. Make it clear to them that not only should they not eat or drink any of the materials, but they should also not directly and repeatedly inhale the fumes emitted by any of them. Students should not be allowed to dispose of the cups and their contents once the experiments are over; do this yourself. Pour the liquid in the cups down the drain with water running, and do not pour the baking soda and bleach one after the other, as an unwanted chemical process may result and damage pipes. The cups and any solid left in them should be wrapped in newspaper and placed into a trash receptacle in a well-ventilated area, preferably outside.
 

Procedure

Begin today's lesson by asking students to think back to last month's science lessons. Ask: Who remembers the names of the five kingdoms into which all living things are categorized? (animal, plant, protist, moneran and fungi) Tell students that in the last lesson, they learned more about plant and animal cells, and learned about two of the structures that plant cells have that animal cells do not, but in today's lesson, they will be learning some surprising facts about cells that belong to organisms in the protist, moneran and fungi kingdoms.

Tell students that one way scientists decide whether an organism is part of the animal or plant kingdom is based on the cell structure. Ask: What two structures within the cell would make one think that an organism belonged to the plant kingdom? (cell wall and chloroplast) For a long time, scientists thought that fungi, like mushrooms, belonged to the plant kingdom because, like plants, their cells have a cell wall. Unlike plants, however, fungi do not make their own food. They get energy from living on dead plants and animals. For this reason, fungi were put into another kingdom by themselves.

When the microscope was invented, scientists began to see new living organisms they had never seen before, and were stumped about how to classify them. Some of these microscopic beings had the features of animals and some had the characteristics of plants. Finally, it was decided that these tiny living organisms would be put into a kingdom all on their own, and it is called the Protist kingdom. Some of the members of this kingdom are so small, they only consist of a single cell! Within this kingdom, the organisms that capture their own food like animals are called "protozoans." (Write on the board.) (If time permits, tell students that in Greek, "proto" means early and "zoan" means animal.) Students may be familiar with the members of this kingdom that act more like plants, in that they contain chlorophyll and make their food. These members include some types of algae, which students may have seen floating on the top of a pond or within an aquarium.

The third kingdom, which like the protist kingdom was only discovered with the use of a microscope, is the moneran kingdom. For a long time, scientists didn't know how to classify these organisms. Then it was discovered that the cells of monerans are quite different from those of the organisms in the protist and fungi kingdoms. The difference--that moneran's cells had no nucleus--was considered so important that these organisms were put into their own kingdom. The two main types of monerans are bacteria and blue-green algae. Ask: What do you know already about bacteria? (It is expected that students will know that bacteria can cause disease.) Tell students that though this is true, bacteria can also be helpful. They are necessary to break down decaying material in the soil to help nourish plants, and all humans have bacteria in their digestive systems that are necessary for proper digestion.

Tell students that today, they will be starting an experiment with bacteria. Ask: Why do scientists conduct experiments? (Answers will vary but should include: to discover new facts, to answer questions, to develop new inventions, etc.) Tell students that they have been challenged to find out which environment, of a set of different environments, is the most conducive to bacteria growth. Their experiment, like all experiments, then begins with a question or problem. Ask: How can you phrase the question you will hopefully answer through this experiment? (Answers will vary but the class should settle on a question similar to: Which environment allows for the most bacteria growth?) Write this question on the board.

Tell students that they will now find out about the different types of environments they will be creating. All of the environments will consist in part of a liquid that is bouillon and water. (If students do not know what bouillon is, explain that it is a liquid that is produced by cooking poultry or meat. The liquid is then dried, and when water is added to it, it dissolves to make a broth.) The bouillon mixture will go into four clear plastic cups, but then, four substances will be added to the cups to make the solution in each cup different. Tell students that one tablespoon of the following substances will be put into each cup: (write on board) salt; sugar; baking soda; bleach.

Then, ask students if, when watching a TV show or reading a book, they try to guess the ending. Discuss with them that predictions are made constantly in many areas of their lives. Several examples, other than the ending of a TV show or book, include what the weather will be like so they know what to wear, how their mothers will react when they show up late for dinner, and how someone will like a gift they are picking out for them. Ask students to give examples of other times in daily life that predictions are made.

Tell students that science is no different. Predictions are made in experiments, too! Tell students that they will be put into groups, and the groups will be told to predict which environment will grow the most bacteria the fastest. Ask: How can they increase their chances of making a correct prediction, in this or any situation? (Think about what you already know about the subjects involved.) They should do this, in groups, regarding the elements that will be added to the bouillon mixture. Put students into groups and have them discuss what they know already about salt, sugar, baking soda and bleach, and make a prediction regarding which, when added to bouillon and water, will allow for the most bacteria to grow.

Tell students that the prediction they just made answers the question that the class composed, but it is only an educated guess. Ask: What do you need to do to in order to get an answer to the question that is more than just a guess? (perform an experiment) Tell students that although they have been told the basis of the experiment, to monitor bacteria growth in a variety of given situations, they need to now think about the specifics of the experiment. Ask: What will they do first? (pour the mixture into the clear plastic cups) Does it matter how much of the mixture goes into each cup? Why should all the cups have the same amount of mixture?

Distribute the cups and the water and bouillon mixture to groups. Have them mark the liquid level on one cup, then pour this same amount into each plastic cup. Ask: What should be done next? (Answers will vary. Prompt students to see that it makes sense to label the cups with the name of the substance that will be added to each cup so that the cups do not get mixed up.)

What will be done after that? (The substances should be added to each cup.) Does it matter how much of each substance is added? Why should the same amount of each substance be added to each cup? Pass out the substances, reminding students of the safety concerns addressed in the Teacher Background, and have students add them to the appropriate cups. Then, the cups should be placed in a well-ventilated area where they will not be disturbed, keeping each team's cups grouped together.

Once excess supplies have been collected or thrown out, (but keeping students in groups) tell them that they just participated in a process that is much like the process scientists go through when they conduct an experiment. This process is called, appropriately, the scientific method. Pass out "The Scientific Method" sheet to each student. Ask: What was they first thing they did regarding the experiment, before they even began to mix the substances? (compose a question or problem that would be answered or solved through the experiment) Looking at the sheet you just received, what is this step called in the scientific method? (purpose) Ask a volunteer to read the information about this first step.

Ask: After you came up with a question, what was, in groups, done next? (A guess was made regarding the answer to the question.) What step is this in the scientific method? (step two: hypothesis) Ask a volunteer to read the information under this step as well.

Tell students that it only made sense to them to then perform an experiment to test the hypothesis, and this too is one of the steps within the scientific method. Ask a volunteer to read step three out loud.

Ask: Without reading the rest of the sheet, what would you guess to be the next logical step in performing the experiment? (to note the information produced by it) Tell students that indeed, this is the next step of the scientific method, and have a volunteer read it aloud.

Tell students that this data would be worthless unless it was finally used to answer the question. The last step of the scientific method addresses this need. Ask a volunteer to read it aloud.

Inform students that each group will now be given two forms that will allow them to record the performance of the experiment. Distribute to each group the Bacteria Experiment Worksheet and the data collection chart, and designate a recorder within each group to do the writing for today. Instruct recorders to fill in the names of their teammates, then to copy the experiment purpose from the board. Each group should have their own hypothesis, and this should be written on the appropriate line as well.

Now have students look on the back of the Bacteria Experiment Worksheet and observe the chart that has been provided for them to record their data. Have them also look at step four of the scientific method and ask: What do you think you should do in the spaces provided on the worksheet? (Write, using as much detail as possible, what the mixture in each of the cups looks and smells like.) Explain that cloudiness (not lightness in color, as this will occur almost immediately in the bleach cup) and an odor other than that of bouillon will indicate bacteria growth. Tell students that their observations, because of space limitations, will need to be a couple well-chosen words. Ask: What words might you use to describe how the mixture looks? (cloudy, bubbly, lumpy, light gray, etc.) Explain why these will allow for a more scientific observation than using words like disgusting, nasty, etc. Ask: What words might you use to describe how a mixture smells? (yeasty, sour, sharp, etc.) Again, tell students that descriptive words such as these are much better than words that may also apply, such as gross, but would be less accurate. Ask: What else will you need to record each time you observe the experiment? (the date) What safety measures should you keep in mind? (Sniff the odor from the cups carefully, not breathing in too much of the fumes, do not drink any of the mixtures, etc.)

Once the experiments have been set up, briefly discuss expectations the teams have regarding the experiment. Have teams share their hypotheses, and ask them to justify why they chose the substance they did as likely to grow the most bacteria. Ask: What influences and events, or occurrences, could influence the outcome of the experiment? (Answers will vary, but should include influences such as light and heat, as well as occurrences such as a spill of the contents of a cup, or a mistake in recording.) Have students find the space on their Bacteria Experiment Worksheet labeled "variables." Tell them that they should record anything they observe that they feel would influence the outcome of the experiment in this space. (Be sure that students know that for some experiments, comments under "variables" may not be needed.)

Collect the Bacteria Experiment Worksheets, the data collection chart and the Scientific Method worksheets for future use. (If you opt to follow up with a quiz on the scientific method, tell students that they need to carefully store the Scientific Method worksheet and study it as homework.)

In the days to come, when time allows, you should have group members observe the experiment and record their findings on their group's data collection chart. This should be done by pairs of students who belong to the same group, and does not need to be done as part of a science lesson, but can be done any time there are a few moments in which students can do it. Ideally, all groups will collect data on the same day. If this is impossible, have groups do so on days as close together as is possible, so that the experiments generally follow the same procedure. Each team member should have at least one opportunity to observe and record findings.
 

Suggested Follow-up Activities

Quiz students on the steps of the scientific method. Before doing so, challenge them to create a mnemonic device for remembering these steps. The first letters of the steps are: PHEDA. One example of a mnemonic device they could use to remember them is: Purple hippos enjoy dreamy afternoons.
 

Have students research the protist, moneran or fungi kingdom using the books or websites suggested.
 

If you have access to a microscope, allow students to design their own experiments using the microscope and following the scientific method. There are several suggested books that contain excellent ideas for investigations using a microscope, and students could use them as springboards for their own experiments.
 

It is hoped that as the lessons is this unit are completed, some of the questions about cells, generated as a part of the K-W-L chart begun in Lesson 24, will be answered. As a follow-up to this lesson, students may research the answers to questions not yet answered and either share their information in an informal presentation, or when the topic comes up in the following classes in this unit.
 
 

THE SCIENTIFIC METHOD


 
 

STEP ONE: PURPOSE

Develop a question you would like to have answered, or a problem that needs to be solved. What do you want to find out? The question or problem will be the focus of the experiment.
 

STEP TWO: HYPOTHESIS

Think about what you already know about the subject. Based on this, make an educated guess, called a hypothesis, that answers the question or solves the problem described in step one.
 

STEP THREE: EXPERIMENT

This step will determine whether or not the hypothesis is correct. In this step, you need to design, set up and perform the experiment.
 

STEP FOUR: DOCUMENT

Record the data that is produced as a result of the experiment. What happened when you performed the experiment? The more detailed your documentation (writing) about what you observed is, the better.
 

STEP FIVE: ANALYZE AND CONCLUDE

Study the data that you recorded. What do the results mean? Draw a conclusion based on the purpose. Was your hypothesis correct? Even if it was incorrect, what did you learn?
 
 
 

BACTERIA EXPERIMENT WORKSHEET
 

GROUP MEMBERS:__________________________________________________________
 

___________________________________________________________________________
 

EXPERIMENT PURPOSE:______________________________________________________
 

___________________________________________________________________________
 

HYPOTHESIS:_______________________________________________________________
 

___________________________________________________________________________
 

VARIABLES:_______________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 
 
 

ANALYZATION AND CONCLUSION:__________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 

___________________________________________________________________________
 
 
 

Fifth Grade - Science - Lesson 26 - Surprising Cell Facts and the Scientific Method
 
 
 
Salt Sugar Baking Soda Bleach
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Fifth Grade - Science - Lesson 27 - Cell Division and Organization
 

Objectives

As a class, complete a sequence chain detailing cell division.

Role play the organization of cells into tissues, which then form organs, which in turn form systems.
 

Materials

Diagram of cell division for transparency (attached)

Cell division worksheet, one copy for each student (attached)

Classroom-size sequence chain on chart paper or blackboard

One sheet of poster or chart paper with "SYSTEM" written on it

Three 8 x 11 inch sheets of paper with "ORGAN" written on each

Six large index cards, or halves of 8 x 11 inch paper, with "TISSUE" written on each

Twenty (or more or less depending on class size) small index cards with "CELLS" written on each
 

Suggested Books

Student Reference

Bender, Lionel. Atoms and Cells. New York: Gloucester Press, 1990. Cell division is covered on pages 22-23, and on page 23 is a magnificent photo of a cell dividing.

Fichter, George. Cells. New York: Franklin Watts, 1986. The author does an outstanding job of describing cell division on pages 46-47.

Teacher Resource

Kapit, Wynn and Lawrence M. Elson. The Anatomy Coloring Book. New York: HarperCollins College Publishers, 1993. This book gives a detailed description of cell division on page four.
 

Website

http://www.cellsalive.com/ Specific to this lesson, this website contains photographs and descriptions of bacteria dividing.
 

Teacher Background

In this lesson, students learn how the nucleus of a cell divides to create two new cells. They are also involved in active role play to review how cells are grouped to form tissues, how tissues are joined to form organs and that in complex organisms, these organs then form systems.

Students have learned about this organization in Second Grade, so the latter part of the lesson acts as a review of this content. To accomplish this role playing, each student is given the role of cells, tissue, organ or system. The roles have been divided as noted under materials, and the role numbers provided will work for a class of thirty students. If you have more students, give out additional cells roles, and if less, assign less. If the number of cells roles is adjusted, you will need to compensate during the class by having each person in the role of tissue group more or fewer students with the role of cells.
 

Procedure

Begin today's lesson by asking students to name the parts of a typical animal cell (cell membrane; cytoplasm; nucleus; nuclear membrane; vacuole; mitochondria). If time permits, briefly review the function of each of these parts. Tell students that when one cell becomes two cells, the cell basically divides itself in half. In order for the each half to have all the information it needs, the cell copies and divides one of these parts to begin the new cell. Ask: Which one of the organelles do you think the cell copies? Why? (Answers will vary.) Tell students that it is the nucleus that divides and in order for them to understand all of the steps in cell division, a sequence chain will be completed. Inform them that the first thing that happens in cell division is that the cell copies the information in the nucleus, and write "nucleus information copied" in the first step of the sequence chain. On the transparency, uncover to show step one, illustrating this. Tell students that in order for the nucleus, which now contains a copy of all of the important cell information, to divide, the nuclear membrane must dissolve, and this happens next. (Write "nuclear membrane dissolves" in the second step of the sequence chain and define the word dissolve if necessary.) Ask: Why would the membrane need to dissolve? (It acts like a wall around the nucleus, and its presence would prevent the nucleus from dividing.) Now reveal step two on the transparency.

Though the cell information has been copied, the each piece of copied information is right next to the original piece of information. To prepare for the divide, all of the copied information is now separated from the original information and all of the "copies" are pushed to one side of the cell and the "originals" are pushed to the other side of the cell. (Write "copied information separated" in the third step of the sequence chain and uncover step three.)

Now, a new membrane forms around each group of information, so that the cell has two nuclei. (Write "new membranes form" in the fourth step of the sequence chain and uncover step four.) Ask: What do you think happens next? (Answers will vary.)

Tell students that a crease then forms in the middle of the cell, separating the two nuclei and pinching the cell in half. Two new "daughter" cells are born! (Write "crease forms to divide cell" in the fifth step of the sequence chain and uncover step five on the transparency.) Inform students that each of the daughter cells are about half the size of the original "mother" cell, but will continue to grow, and when full size, will divide themselves. Cell division can take as little as twenty minutes, but is also known to take up to three hours or even longer.

Sometimes, when the cell makes a mistake in copying the information in the nucleus, the new cell with the copied information is abnormal, and is called a mutant (write on the board). Usually, mutant cells are unable to perform their job well and die quickly, but if a mutant cell is more capable of living in the surrounding environment than the original cell, it will begin a change in the organism to which it belongs. (If time permits, briefly discuss how this relates to movies and TV shows students may know with "mutant" in their title, such as "Teenage Mutant Ninja Turtles.")

If time permits, pass out the cell division worksheet and have students cut out and properly order the steps in cell division. Once the steps are sequenced properly, students should describe on the lines given, using brief phrases in their own words, what is occurring in each step. They should be able to do this without the aid of the transparency or the sequence chain. When students have finished, either review it orally or collect it for grading purposes.

Now that students know how cells divide, tell them that they will review what happens when cells combine. Remind students that the human body is made up of cells, but when they look at the human body, they do not see just a mass of cells. Instead, they see hair, skin, eyes, etc. which show that the cells of the body have been organized into groups. Tell students that to review how cells within the body are organized, they will each get a role to play. Randomly pass out the various sized sheets of paper, poster board and index cards, with roles written on them. Tell students that they already know that the body is made up of lots of cells. Ask that all students with the role of "cells" stand up. Tell them that when cells with the same function are organized together, they form tissues. Some examples of this are skin tissue or muscle tissue in animals, and in plants, the skin of an onion or the bark of a tree. Have the students who are assigned the role of "tissue" gather two students with the role of "cells" around them, then stand in front of them so that the majority of the class can see the word "tissue." The tissue and his or her cells should be separate from other tissues and cells. Remind students that the cells that are grouped together into a tissue all perform the same job.

Tell students that each of the six tissues now present in the classroom have a different job, but for some of them, their jobs are similar, even if they are not exactly the same. Ask: Does anyone know or remember from Second Grade what tissues with similar jobs form when you put them together? (organs) Ask that all the students with the role of "organ" now stand. They should group together two tissues and the tissues' surrounding cells. The students who have the organ role should then stand in front of their tissues and cells, and should be clearly separated from the other organs in the room, which will probably mean that there are three large groups in three corners of the room. Tell students that the tissues have been organized into organs, and that examples of organs they may be familiar with are the heart, stomach or brain in animals, and in plants, the root or flower.

At this point in the role playing, there should be only one student left in his or her seat, the student assigned the role of system. Ask students to predict the next step of organization. (Organs that work together are grouped into systems.) Tell students that indeed, in complex organisms, organs working together are organized into systems. Ask: Can you remember any systems within the human body you learned about in Second Grade? (the circulatory system, the digestive system and the excretory system) Tell students that now, the organs will be organized into one system. Instruct the student with the role of "system" to gather the organs, which are comprised of tissues and cells, into one large group (the whole class)

Now have students all go back to their seats, and congratulate them on their successful portrayal of cell organization. To summarize the lesson, complete the cell organization triangle (below), with student assistance, on the board. Once this has been done, challenge the students to, on their own on a sheet of paper, recreate the triangle by building it the opposite way than was done together. (If you started with cells, they will start with system, and vice versa.)

Note: Students should continue to be monitoring the experiment they began in Lesson 26, and recording the data on the data collection charts. The charts should be completed prior to the next lesson, and once they are complete, the cups and their context should be disposed of.
 

Additional Activity

Assign a system and ask students to do a breakdown of its components. It would be expected that they would be able to name the organs within the system, to tell what type of tissue each organ is made of, and to describe at least several of the cell types that comprise the tissues.
 

Fifth Grade - Science - Lesson 28 - Ernest Just and the Experiment and Unit Conclusion
 

Objectives

Analyze and conclude the results of the experiment begun in Lesson 26.

Complete the third part of the K-W-L chart.

Listen to the accomplishments of Ernest Just.

Employ personification in writing a paragraph entitled "My Life as a Cell in Ernest Just's Laboratory."
 

Materials

Transparency or chart of the steps of the scientific method (from Lesson 26)

Each group's Bacteria Experiment Worksheet and completed data collection chart (begun in Lesson 26)

The K-W-L chart begun in Lesson 24

One copy for each student of the cell personification worksheet (attached)
 

Suggested Books

Hayden, Robert. 7 African American Scientists. Frederick, MD: Twenty-First Century Books, 1992. Chapter three is devoted to Ernest Just and, though somewhat lengthy (26 pages), is written in a style both appealing to and appropriate for fifth graders.

McKissack, Patricia and Frederick. African-American Scientists. Brookfield, CT: The Millbrook Press, 1994. Pages 28-40 are about Ernest Just and include a helpful time line of his life as well as suggestions for further reading.

Yount, Lisa. Black Scientists. New York: Facts on File, Inc., 1991. The accomplishments of Ernest Just are summarized on pages 69-73. On page 71 is a photo of Dr. Just in his laboratory.
 

Teacher Background

In today's lesson, students first analyze and conclude the results of the experiment they started in Lesson 26 on bacteria growth. Once this has been done, they complete the K-W-L chart begun at the start of the unit. Finally, they hear about Ernest Just and write a paragraph in which they use the literary tool of personification to describe what life as a cell in Dr. Just's laboratory would be like. Students were taught in third grade that personification is the giving of qualities of a person to other living and nonliving things. They were exposed to personification again in Grades Four, and earlier this year in Grade Five.

Prior to this lesson, students should have completed the data collection chart noting their observations on bacteria growth as a result of the experiment.
 

Procedure

Begin today's lesson by displaying the steps of the scientific method. Ask: Which steps have been completed so far in the bacteria experiment? (steps one through four) What still needs to be done? (step five) Ask a volunteer to read step five aloud. Tell students that they will now complete step five, and put students into the bacteria experiment groups.

Pass out to each group their Bacteria Experiment Worksheet and data collection chart. Remind students that odor and a cloudy appearance were indicators of bacterial growth. Looking at the data collection chart, which of the cups had any bacterial growth? (Answers may vary slightly from group to group.) Have groups study the data and discuss it amongst themselves to determine which cup, in their estimation, had the most bacteria growth. Once groups have determined this, have them use the lines under "Analyzation and Conclusion" on their Bacteria Experiment Worksheet to answer the following questions in a paragraph format. (Write the questions on the board or overhead.)

--What conclusion can be drawn from the experiment? (Your conclusion should answer the question posed in the purpose.)

--Was your hypothesis correct? Why or why not?

--Do you think any of the things your group noted under "Comments" affected the outcome of the experiment? If so, how?

--What other conclusions can be drawn from the results of the experiment? (What else did you learn?)

Ask groups to share what they have written, and then ask students to make further observations and conclusions based on the information provided by the class as a whole. Did one substance definitely create the best environment for bacteria growth in all, or most, of the experiments? If so, what does this mean about a conclusion that they, as a class can draw? Even if not, again, what does this mean about the conclusion that they, as a class can draw? Was there another substance that everyone, or almost everyone, noted seemed to inhibit bacteria growth? What does the answer to this question mean in terms of another conclusion? Based on this experiment, what characteristics of substances do they think promote or prevent bacteria growth? Based on these inferences, what other substances would they guess promote bacteria growth? What other substances might prevent it? How could they perform another experiment to test these theories to see if they are right? Congratulate students on their insightful observations and collect the Bacteria Experiment Worksheets and the data collection charts for grading purposes.

Display the K-W-L chart and ask students to silently read what was written under the K and the W. Ask: What questions were answered, and what were their answers? (As students volunteer this information, write it under the L, for learned.) What else did they learn about cells as a result of their study during this unit? (Write these answers under L also.)

Tell students that in completing this unit on cells, especially the part of it in which they performed an experiment, they acted very much like a famous African-American scientist, Ernest Just. (Write this name on the board.) Inform students that Ernest Just was born in 1883, a time when there were not very many good schooling or job opportunities for African-Americans in this country. Though he faced prejudice and had very little encouragement, he eventually earned his degree in biology from Dartmouth College. Just was especially interested in marine cell biology (write this on board and explain to students if necessary that this is the study of cells from animals that live in the ocean). His studies in this field earned him a doctorate and he went on to teach at Howard University. Recognizing his importance in proving that African-Americans could achieve greatness in laboratory sciences, the N.A.A.C.P. awarded him the very first Springarn Medal in 1915, when he was only thirty-one. Just became well-known for his method of studying cells. Like the scientific method that students just used, his method helped to ensure that his experiments were accurate and correctly measured what he intended for them to. He focused his studies on the cell surface and the cytoplasm (write these two on the board) and was ahead of his time in recognizing the importance of the interaction between cell parts.

Tell students that they will be participating in an exercise in personification. Ask: What is personification? (Accept all reasonable answers that show that students understand that personification involves the act of giving the qualities of a person to other living and nonliving things.) Tell students that by using personification, one could give an eraser the ability to feel emotions (I'm so bored! Back and forth, back and forth, that's the only thing I do all day!) or a dog the ability to talk ("This dog food is disgusting! How about some meat loaf for dinner instead?") Ask students to think about how they would personify a pencil. How might a pencil feel, emotionally? What might a pencil think? Why might a pencil believe it is important? How might it feel about being sharpened?

Inform students that the personification they will be completing on their own will be one in which they take on the role of a cell in Dr. Ernest Just's laboratory. Pass out the cell personification worksheet and review it with students. As the worksheet directs, they should write a paragraph in which they describe their life. They will want to consider what they know about Ernest Just and what they know about cells. (Continue to display for student use the information about Just on the board and the L portion of the K-W-L chart.) They should also consider the questions posed on the worksheet, but shouldn't limit themselves to these questions. When finished, they may want to draw a picture to accompany the description of their life. If time permits, allow volunteers to read their paragraphs aloud and show any accompanying pictures.
 

Suggested Follow-up Activities
 

Display the paragraphs and pictures on a bulletin board entitled "My Life as a Cell in Dr. Just's Laboratory."
 

Students may actually write their suggestions on how to test their theories regarding which other substances inhibit or promote bacteria growth. Ask them to do so and consider the suggestions experiment proposals. Select one or two of the best and allow students to perform them in the classroom.
 

Assign students the task of finding examples of substances that kill bacteria or inhibit bacteria growth. They may find these examples advertised on TV, in print, on the radio, etc., or they may find them within their own homes, (using the labels or boxes to determine anti-bacterial claims). They should write the name of the product and its claim regarding bacteria. When all students have finished the assignment, the products should be compared and contrasted. Which ones claim to kill bacteria? What do they have in common? Which ones claim to fight bacteria, or stop bacteria from growing? What do they have in common? How are these two groups different? How do these products support or refute the ideas the class had, after the experiment, about the characteristics of substances that promote or prevent bacteria growth? What types of experiments do they think the manufacturers of the products performed in order for them to make the claims they do about their product?
 

Ernest Just and the Experiment and Unit Conclusion
 
 

My Life as a Cell in Ernest Just's Laboratory


 
 

Write a paragraph, with the above title, describing what your life would be like if you were a cell in Dr. Just's laboratory.

Give yourself as many human characteristics as you would like, but remember to include aspects of what you have learned about cells, and what you know about Ernest Just. Consider the following questions in your writing:
 

What kind of cell are you? (Are you part of a tissue/organ/system?)
 

What is your shape or function?
 

Why do you think Dr. Just keeps looking at you?
 

How do you feel about being studied?
 

What other cells do you consider to be your friends? Why?
 

What was cell division like for you?
 

Which of your parts do you consider to be the most important? Why?
 
 

Bibliography


 
 

Student Reference

*Bender, Lionel. Atoms and Cells. New York: Gloucester Press, 1990. (0-531-17219-8)

Berger, Melvin. Germs Make Me Sick. New York: HarperCollins, 1985. (0-06-445053-8)

Bleifeld, Maurice. Experimenting with a Microscope. New York: Franklin Watts, 1988. (0-531-10580-6)

Coldrey, Jennifer. Discovering Fungi. New York: The Bookwright Press, 1988. (0-531-18170-7)

Cole, Joanna. The Magic Schoolbus Inside the Human Body. New York: Scholastic Inc., 1989. (0-590-41427-5)

Cosgrove, Margaret. Wonders Under a Microscope. New York: Dodd, Mead and Company, 1959.

*Fichter, George. Cells. New York: Franklin Watts, 1986. (0-531-10210-6)

Froman, Robert. Mushrooms and Molds. New York: Thomas Y. Crowell Company, 1972. (0-690-56602-6)

Hayden, Robert. 7 African American Scientists. Frederick, MD: Twenty-First Century Books, 1992. (0-8050-2134-5)

McKissack, Patricia and Frederick. African-American Scientists. Brookfield, CT: The Millbrook Press, 1994. (1-56294-372-3)

Villiard, Paul. The Hidden World: The Story of Microscopic Life. New York: Four Winds Press, 1975. (0-590-07307-9)

Young, John K. Cells. New York: Franklin Watts, 1990. (0-531-10880-5)

Yount, Lisa. Black Scientists. New York: Facts on File, Inc., 1991. (0-8160-2549-5)
 

Teacher Resource

Dashefsky, H. Steven Microbiology: 49 Science Fair Projects. New York: TAB Books, 1994. (0-07-015660-3)

Grambo, Gregory, Dean Medley and Kelly Medley. "Life is a 'Cell-ebration!'" The Mailbox. October/November 1995, 37-43.

Hirsch, E.D. What Your Fifth Grader Needs to Know. New York: Doubleday, 1993. (0-385-41119-7)

Kapit, Wynn and Lawrence M. Elson. The Anatomy Coloring Book. New York: HarperCollins College Publishers, 1993. (0-06-455016-8)

Lammert, John M. Science Fair--How to do a Successful Project: Microbes. Vero Beach, FL: Rourke Publications, Inc., 1992. (0-86625-430-7)

Sund, Dr. Robert B., Dr. Donald K. Adams and Dr. Jay K. Hackett. Accent on Science. Columbus, OH: Charles E. Merrill Publishing Co., 1982. (0-675-07653-6)

*Required or strongly recommended