Fourth Grade - Science - Overview -March

Lessons 34, 35 and 36 are intended to precede the performance assessment practice tasks. While knowledge of the content of these lessons is not necessary for success in the following performance assessment tasks, familiarity with the structure of an atom and elements and compounds will add dimension to the tasks and contribute to the confidence level of the students. Performance assessment tasks are best used in sequence.

Fourth Grade - Science - Lesson 34 - Chemistry

Objectives

Identify the three states of matter and give examples of each.

Identify the particles of an oxygen atom and label them as positively or negatively charged.

Materials

Small container of baking soda, small clear container of vinegar, measuring spoons, 1-liter plastic soda bottle, an 18-inch balloon, tape

Three-foot length of string with a key or ring securely tied on the end

Diagram of an oxygen atom for transparency

Two bar magnets

Structure of an atom worksheet

Suggested Books

Ardley, Neil. The World of the Atom. New York: Gloucester, 1989. Contains illustrations of atom models showing the shells of electrons.

Berger, Melvin. Atoms, Molecules and Quarks. New York: Putnam, 1986.

________. Our Atomic World. New York: Franklin Watts, 1989.

Edom, Helen. Science With Water. London: Usborne, 1990. Contains simple activities highlighting the properties of liquids.

Glover, David. Solids and Liquids. New York: Kingfisher, 1993. Describes the properties of the forms of matter and includes activities.

Gregoire, Tanya. Museum of Science Activities for Kids. Holbrook, MA: Adams Media, 1996.

A lively and clearly-written explanation of matter, atoms and molecules can be found on page 43. There are also chemistry activities such as creating a polymer with glue and borax.

Mebane, Robert C. Water and Other Liquids. New York: Twenty-First Century, 1995.

While these experiments are intended for older students to do at home, some of them are suitable for demonstrations in the classroom.

Procedure

Write matter on the board. Ask: What is matter? Is there matter in this classroom? (Yes, everything is made of matter. Remind the students that anything that takes up space is matter. Write takes up space next to matter. Ask: Is the board made of matter? (Yes, it takes up space.) Is the chalk matter? (yes) Are you matter? (yes) Is a tiny grain of sand matter? (yes) Ask: Is air matter? (yes) Point out that air takes up the space around us. Ask: Does matter ever change or does it always stay the same? (It changes.) Ask the students to give some examples of changes in matter. Make a list on the board. Answers might include ice melts and becomes water, wood burns and becomes ash, water boils and becomes steam, rain turns dirt to mud, vegetables rot, iron rusts, food we eat becomes energy and waste products, things break. Remind the students that matter comes in three states. Ask: What are the three states of matter? (solid, liquid, gas) Ask the students to give some examples of solids, liquids and gases. Answers might include solid: rock, desk, sand, chocolate bar, dirt, apple; liquid: water, oil, soda, milk, gasoline, honey; gas: oxygen, helium, car exhaust, steam, cooking gas.

Tell the students that you are going to make matter change right before their eyes. Show the students the bottle, balloon, baking soda and vinegar and ask them to identify the forms of matter (Vinegar is a liquid. Baking soda, bottle and balloon are solids.) Tell the students that you are going to combine a liquid and a solid to form the third form of matter--a gas. Pour a teaspoon of baking soda into the bottle. Pour three tablespoons of vinegar into the balloon. Stretch the open end of the balloon over the neck of the bottle and secure it with tape. Allow the balloon to hang down so the vinegar does not drain into the bottle. When you are ready, lift the balloon so the vinegar runs into the bottle. The mixture will fizz; the balloon will inflate. Ask: How did you know a gas was formed? (It blew up the balloon.) Would you have known a gas was formed if the balloon had not been there? How? (fizzing bubbles) Point out that the combination of this particular liquid (vinegar) and this particular solid (baking soda) produced a gas called carbon dioxide. Remind the students that carbon dioxide is the same gas that is pushed out of our lungs when we breathe out. It also makes the fizz in soda. Ask: Have I changed matter? (yes)

Ask: If everything that takes up space is made of matter, what is matter made of? (Accept all answers.) Write atoms on the board. Tell the students that all matter is made of tiny bits called atoms. Atoms are so tiny, that you cannot see them, even with the most powerful microscopes in the world. They are so tiny that if every person on the planet were an atom, we would all fit on the head of a pin. Billions and billions of atoms make up all matter. What makes a tree a tree or an orange an orange is the way atoms are arranged. Tell them that when you changed the baking soda and vinegar into carbon dioxide, you rearranged atoms. Atoms are the building blocks of matter.

Tell the students that if scientists invented a special microscope to see an atom--an atom spyer-they think they know what an atom would look like. Show the students the string and the key. Make sure there is plenty of space around you and demonstrate by holding the end of the string securely and whirling the key, lasso-style, around and around, faster and faster. You can spin it over your head or to the side. Tell the students that scientists think what you would see when you looked through the atom spyer at an atom is a blur of motion. That is because tinier bits--particles that make up atoms--are whirling around like the key. They whirl around so fast that an atom would look like a blurry ball.

Show the students the transparency of an oxygen atom. Point out that atoms are made of particles. If we could see through the blurry motion to the center of the atom, scientists think we would see two kinds of particles packed together in a nucleus. Point out that the nucleus is like your hand holding the string while the key swung around it. The particles whirling around like the key are called electrons. Some atoms have lots of electrons, some have only one. Ask: How many electrons in this atom of oxygen? (eight) Point out that some of the electrons are orbiting closer to the nucleus while others are in an outside ring. Ask the students if the electrons orbiting a center remind them of planets orbiting the sun. Point out that in between the sun and planets is lots of empty space. In between the nucleus and the electrons is also empty space.

Ask the students to look closely at the nucleus. Ask: From the diagram, can you tell what the two kinds of particles in the nucleus are called? (protons, neutrons) Point out again that atoms have three kinds of particles: protons and neutrons in the center and whirling electrons moving around the outside. Ask: What keeps planets circling around the sun instead of flying out into space? (the sun's gravity) Tell the students that a force keeps the electrons from flying away from the nucleus, too, just as the string holds onto the key whirling in a circle. Point out on the transparency that electrons have a negative electrical charge (-). Protons have a positive charge (+). Positively and negatively charged particles are pulled toward each other in the same way that north and south poles of magnets are. Demonstrate this with two magnets. Point out that the opposite poles attract just as positive and negative charges are attracted to each other. Opposites attract. This attraction between the positively-charged protons and the negatively-charged electrons holds atoms together. It causes the electrons to whirl around the nucleus. Point out that on the diagram neutrons have no electrical charge. Note that students counted 8 electrons circling in the oxygen atom. Tell the students that there are exactly the same number of protons in the nucleus-8 protons. The number of negative electrons and the number of positive protons are in balance. Suggest that a way to remember which particle is positive and which is negative is to remember that positive and proton both begin with "p."

Possible Homework

Have students identify the particles of an atom on the worksheet (attached) and label them. Have them also indicate + or - on particles to indicate whether they are positively or negatively charged.

Fourth Grade - Science - Lesson 35 - Chemistry

Objectives

Identify the charges of protons, neutrons and electrons.

Review behavior of water molecules as solid, liquid and gas.

Identify numbers of atoms of elements in molecules by their chemical formulas.

Materials

Pitcher and glass of water

Diagrams of hydrogen and oxygen atoms for transparency

A steel wool scrub pad (non-soap type found in hardware stores), jar with lid, water

For each student: A chemical formula worksheet

Suggested Books

Ardley, Neil. The World of the Atom. New York: Gloucester, 1989.

Berger, Melvin. Atoms, Molecules and Quarks. New York: Putnam, 1986. Although this book is a little advanced for fourth graders, Berger's description of the unseen world of subatomic particles is highly readable.

________. Our Atomic World. New York: Franklin Watts, 1989.

Gardner, Robert. Experiments with Bubbles. Hillside, NJ: Enslow, 1995. On page 63-65 there are several activities dealing with carbon dioxide bubbles.

Gregoire, Tanya. Museum of Science Activities for Kids. Holbrook, MA: Adams Media, 1996. Page 237 includes a read aloud section on hydrogen and oxygen atoms and the formation of water molecules.

Procedure

Remind the students that last lesson they learned about tiny bits that make up matter. Ask: What do we call these tiny bits? (atoms) Tell the students that there are over 100 different kinds of atoms that make up matter. Tell them that when atoms of the same kind bind together, they make elements. Write elements on the board. Tell the students that gold, silver and lead are all elements. Gold is made of only gold atoms; silver is made of only silver atoms; lead is made of only lead atoms. Ask: Are gold, silver and lead solids, liquids or gases at room temperature? (solids) Tell the students that two elements we breathe are oxygen and nitrogen. Ask: Are oxygen and nitrogen solids, liquids or gases at room temperature? (gases) Tell the students that an element called hydrogen, also a gas, is the most common element on Earth. It is also the smallest atom--it has only one electron.

Show the students the transparency of atom models. Point out that the hydrogen atom has only one electron. Ask: How many protons does the hydrogen atom have? (one) Remind them that they have labeled the particles in an oxygen atom. Ask: How many electrons are there in an oxygen atom? (8 electrons) Are the electrons positively or negatively charged? (negatively charged) How many neutrons does it have? (one) Is a neutron positively or negatively charged? (It has no charge.) Point out that the oxygen atom is bigger than the hydrogen atom. Tell the students that when atoms of one element bind with atoms of another element, they make compounds. Write compounds on the board. Point out that 100 different kinds of atoms can combine in many, many different ways to make every kind of matter on the planet. Chemistry is the study of the make up of matter--atoms, elements and compounds--and of how matter changes.

Tell the students that when atoms of elements bind together, the compound they make can be very different from the elements themselves. Pour some water from the pitcher into the glass. Tell the students that this is a familiar compound. Ask: Is this compound a solid, liquid or gas at room temperature? (liquid) Tell the students that we use this compound to wash clothes and dishes, to take baths, and even to drink. Ask: What compound is this? (water) Does anyone know which elements we have been discussing that combine to make water? (hydrogen and oxygen) Point out that both hydrogen and oxygen are gases but that when their atoms bind together they make a liquid--water.

On the transparency, point out the water molecule. Tell the students that this is a model showing how hydrogen atoms and oxygen atoms bind together to make a molecule of water. If atoms are like letters, molecules are like the words they make when they get together. Point out that a water molecule looks a lot like Mickey Mouse. Ask: Looking at the model, how many hydrogen atoms are there in a molecule of water? (two) Write H2 on the board. How many oxygen atoms are there? (one) Write H2O on the board. Tell the students that this is the chemical formula for water. It tells you that you need two atoms of hydrogen and one of oxygen to make a molecule of water.

Ask: Is this compound, water, always a liquid? (no) What is its solid form? (ice) What is its gas form? (steam or water vapor) What causes this compound to change from one form of matter to another? (hot and cold-temperature) What happens to a glass full of ice if you leave it out in a warm room? (The ice changes to a liquid.) Remind the students that heat energy causes molecules to move around and become more active. H2O molecules move away from each other and do not hold together as tightly. More heat energy causes the molecules to speed up even more. They move farther and farther apart until liquid turns to vapor and mixes with the molecules in the air.

Remind the students about the balloon and bottle demonstration from the last lesson. Point out that you combined two compounds, vinegar and baking soda to create a new compound: carbon dioxide. Write CO2 on the board. Tell the students that this is the chemical formula for a molecule of the compound carbon dioxide. Ask: What does the formula say is needed to make a carbon dioxide molecule? (one atom of carbon and two atoms of oxygen)

Write this formula on the board: Fe2O3. Tell the students that Fe is the chemical code for iron. Ask: What is the chemical code for oxygen? (O) Tell the students that Fe2O3 is the chemical formula for a molecule of iron oxide, also called rust. Ask: What does the formula say is needed to make a molecule of iron oxide? (two atoms of iron and three atoms of oxygen) Show the students the steel wool pad, jar and water. Tell them that with these items, molecules of the compound iron oxide can be made. Ask: Where do you think atoms of iron will come from? (scrubbing pad) Tell the students that the scrubbing pad is made of steel wool. Steel is made from iron, so the steel wool pad will be the source of iron for the iron oxide. Ask: Where will the atoms of oxygen come from? (the air inside the jar) Tell them that water is added to speed up the change. Put the steel wool pad in the jar and add a little water. Seal the jar and shake it a few times to moisten the steel wool. Tell the student that since the making of iron oxide takes some time, they should check on the progress of the change over the next few days.

Remind the students that matter is anything that takes up space. Suppose there is nothing taking up space--no atoms of anything, just empty space. Tell the students that empty space where there is no matter is called a vacuum. Ask: Where might we find a vacuum, empty space with not even a single atom of matter? (space) Tell the students that scientists have tried to create vacuums on Earth by pumping all the air out of a container, but there are always a few molecules of matter left to keep the space from being empty. Only in space would you find truly empty space.

Distribute the worksheet and ask the students to use the key to find the chemical codes for elements and then write the numbers of atoms of each element needed to make a molecule of the compound.



Name____________________________________

Decoding Chemical Formulas



Look at the chemical formulas below. To decode the formula, you will need the element codes at the bottom of the page. Write the number of atoms of each element needed to make a molecule of each compound. The first formula is decoded for you. Remember that no number after an element code means one atom.

Substance Formula Decoded
WATER H2O 2 atoms of hydrogen + 1 atom of oxygen
SUGAR C12H22O11
SALT NaCl
RUST Fe2O3
BAKING SODA NaHCO3
VINEGAR C2H4O2
SAND SiO2
CHALK CaCO3


hydrogen=H

sodium=Na

chlorine=Cl

carbon= C

calcium=Ca

silicon=Si

iron=Fe

oxygen=O

Fourth Grade - Science - Lesson 36 - Chemistry

Objectives

Measure the mass of two students.

Calculate the volume of a box by measuring its sides.

Use water displacement to measure the volume of a marble.

Materials

Jar with steel wool pad from last lesson

Rubber glove, white sheet of paper or light-colored styrofoam tray

If available, rusty metal objects, painted metal object

Bathroom scale

For each group of three students: A box, a ruler with inches on one side and centimeters on the other, a graduated cylinder, small pitcher of water, a marble, paper towel for messes

Two slices of soft white bread

Suggested Books

Engel, Holly. Real World Science. Dana Point, CA: Edupress, 1994. Pages 50-51 include an activity for comparing density of liquids.

Gardner, Robert. Kitchen Chemistry. New York: Julian Messner, 1982. Contains chapters such as chemistry in and near the kitchen sink, chemistry in the refrigerator, and chemistry on the kitchen counter.

Glover, David. Solids and Liquids. New York: Kingfisher, 1993. Page 27 includes information on rusting and rotting.

Kim, Hy. Showy Science. New York: HarperCollins, 1994. Includes activities on volume and partial vacuums.

Mebane, Robert C. and Thomas Rybolt. Adventures with Atoms and Molecules: Book II. Hillside, NJ: Enslow, 1987. Dozens of experiments including: Does Air Have Weight? and Is Cold Water More Dense than Hot Water?

Robson, Pam. Clocks, Scales and Measurements. New York: Gloucester, 1993. Pages 22-27 discuss volume, mass and density with full-color illustrations and activities.

VanCleave, Janice. 201 Awesome, Magical, Bizarre and Incredible Experiments. New York: Wiley, 1994. The chemistry section has many easy-to-do investigations that include measurement of volume and density.

Procedure

Show the students the jar with the steel wool pad from last lesson. Ask the students to describe how the steel wool has changed. Ask: Has it changed color? (It is reddish.) Open the jar and take out the steel wool. Have a student come forward and, wearing a rubber glove, crumble the steel wool on a white piece of paper or light-colored styrofoam tray. Show the class the steel wool remains. Ask: What compound is this? (Iron oxide) Write Fe2O3 on the board. Ask: What does the formula say is needed to make a molecule of iron oxide or rust? (two atoms of iron and three atoms of oxygen) Ask the students to describe where else they have seen iron oxide or rust. Answers might include rusty cars, rusty nails, rusty hinges on doors, rusty machinery, etc. If available, show the students some rusty items and a painted metal object. Ask: What do all of these rusty things have in common? (They all have iron in them.) Point out that iron atoms bonded with oxygen atoms to make this reddish compound, iron oxide. Ask: What do people do to keep objects from rusting? (paint them or coat them with a protector) How would this keep iron oxide from forming? (It would keep oxygen and water away from the iron in metal.) Remind the students that atoms of two elements--iron and oxygen--bonded together to make the compound iron oxide.

Ask the students to think about metal rusting and wood burning. Ask: Does matter ever disappear? Do atoms ever disappear? (Accept all answers.) Ask: If matter disappears, where does it go? (Accept all answers.) Tell the students that the answers to these questions are very important because they tell us how everything made of matter (which is everything in the world) behaves. Ask: What do you think happens when metal rusts or wood burns? Do you think atoms of matter are lost or are they just changed into something else, another compound? (Matter is not lost, it is changed into something else.) Write conservation of matter on the board. Tell the students that conservation of matter means that all matter is recycled, used again. Any kind of matter can be broken up and rearranged into other kinds of matter. Atoms are constantly combining into compounds, then rearranging and combining into others. Matter changes, but it does not disappear. On the board next to conservation of matter, write matter changes but does not disappear.

Remind the students that the definition of matter is that it takes up space. Ask: Can a book, a shoe, a bird, or a bus occupy the same space at the exact same moment? (no) Point out that for matter to occupy a space, other matter has to move out of that space. Tell the students that air molecules have to move out of a space when you walk into it. Water molecules have to move out of a space when you swim through it. Tell the students that two atoms cannot occupy the same space at the same time. This is another rule about matter.

Have two volunteers come forward. Point out that because these two take up space, we can call them matter. Ask: How can we measure the amount of matter in these students? (weigh them) Tell the students that the amount of matter in an object is called its mass. Write mass=amount of matter on the board. Have each volunteer weigh himself or herself on the bathroom scale and then write his or her mass on the board.

Pick up a box. Tell the students that volume is the amount of space matter takes up. Write volume=amount of space matter takes up on the board. Ask: How can I measure the amount of space this box takes up? (Accept all answers.) Point out that with a box you could find out its volume by measuring its height, width and depth and then multiplying them. Write on the board volume of a box=height x width x depth and tell the students that this is the formula for volume. Divide the class into groups and distribute boxes and rulers. Have the groups measure and calculate the volumes of their boxes. Point out that since they measured inches in three dimensions--height, width and depth--their answer will be in cubic inches. A cubic inch is one inch high, one inch wide and one inch deep. Tell the students that different countries use different units of measure. In the U.S. and Britain people measure in inches and feet. In other European countries they measure in meters and centimeters. The units of measurement used in science are metric units. Point out that the other sides of their rulers measure in centimeters. Have the groups also measure the boxes in centimeters and calculate the volume in cubic centimeters.

When the students are finished, show them a marble. Ask: How would you measure the volume of this marble? (Accept all answers.) Tell the students that you have an easy way to measure a marble's volume. Remind the students that air molecules and water molecules have to move out of a space when an object moves into it. Ask: What if we measured the air or water that moved out of the marble's space? Would that tell us the marble's volume? (yes) Would it be easier to measure the amount of water or the amount of air that the marble moves? (water)

Give each group a marble, a graduated cylinder and a small pitcher of water. Ask the students to look at the sides of the graduated cylinders. Ask: What unit of measure do you see on the side of the graduated cylinder? (ml) Tell the students that mL stands for milliliter, another metric unit. A milliliter is equal to a cubic centimeter. Write 1 ml = 1 cubic cm. Remind the students that to find out the volume of the marble, they will have to measure the amount of water it pushes out of its way. Ask the students to write down the steps they will take to find the volume of the marble first and then follow the steps to see if they can calculate the marble's volume.

When the groups have finished writing and measuring, record their results on the board. Point out that in order to get their answers, they poured water into the cylinder and recorded the number of milliliters. Then they dropped in the marble and measured the amount of water again. The difference between the two measurements was the amount of water the marble had pushed out of the way or displaced. This way of measuring an object's volume is called the displacement of water method.

Tell the students that they have measured two properties of matter. Matter has mass. They have measured mass or amount of matter. Matter has volume. They have measured volume or the amount of space matter takes up. A third property of matter is density. Matter has density. The density of an object is the amount of matter packed into the space that object fills. Have two volunteers come forward. Give each volunteer a slice of soft, white bread. Ask the two to compare the slices of bread. Ask: Just by looking at them and estimating, do you think these two slices of bread have about the same mass and volume? (yes) Ask one of the volunteers to crush his or her slice of bread into a tight ball. Ask: Which piece of bread do you think now has greater density? (the crushed one) Why? The same amount of matter has been pushed into a smaller space, a smaller volume. Write density=amount of matter packed into the space an object takes up on the board.

Possible Homework

Ask: Could you use the water displacement method to measure the volume of something really big? Describe a big object whose volume you might want to measure and describe how you might go about measuring it using water displacement. Draw a diagram of how it could be done.

Bibliography

Ardley, Neil. The World of the Atom. New York: Gloucester, 1989. (0-531-17145-0)

Berger, Melvin. Atoms, Molecules and Quarks. New York: Putnam, 1986. (0-399-61213-0)

________. Our Atomic World. New York: Franklin Watts, 1989. (0-531-10690-X)

Edom, Helen. Science With Water. London: Usborne, 1990. (0-746-01261-6)

Engel, Holly. Real World Science. Dana Point, CA: Edupress, 1994. (1-564-72174-4)

Gardner, Robert. Experiments with Bubbles. Hillside, NJ: Enslow, 1995. (0-894-90666-6)

________. Kitchen Chemistry. New York: Julian Messner, 1982. (0-671-42102-6)

Glover, David. Solids and Liquids. New York: Kingfisher, 1993. (1-856-97845-1)

Gregoire, Tanya. Museum of Science Activities for Kids. Holbrook, MA: Adams Media, 1996.

(1-558-50633-0)

Kim, Hy. Showy Science. New York: HarperCollins, 1994. (0-673-36091-1)

Mebane, Robert C. and Thomas Rybolt. Adventures with Atoms and Molecules: Book II. Hillside, NJ: Enslow, 1987. (0-894-90164-8)

Mebane, Robert C. Water and Other Liquids. New York: Twenty-First Century, 1995. (0-805-02840-4)

Robson, Pam. Clocks, Scales and Measurements. New York: Gloucester, 1993. (0-531-17419-0)

VanCleave, Janice. 201 Awesome, Magical, Bizarre and Incredible Experiments. New York: Wiley, 1994. (0-471-31011-5)