Elementary Science ACTIVITIES

Transcription

1 Elementary Science ACTIVITIES

2 Table of Contents Introduction Properties of Matter Mixture I Mixture II What s Magnetic? Solutions Emulsion Layers Separating a Suspension What Do Liquids Do? Solids, Liquids, and Gases Modeling Solids, Liquids, and Gases Viscosity Sun and Earth Night and Day Moon Phases Perpendicular and Oblique Rays Inclination of the Earth s Axis Shadow Lengths Heat Energy from the Sun The Layers of the Earth Living Things Cool Beans Beans in a Bag Smart Plants Smart Plants II Behavior of Fluids Balloons Hot and Cold Water Gases Hot Air Balloon Rising Water Stubborn Baggie Plunger Air Pressure Pressure in Liquids Drops on a Penny Floating Paper Clip Fleeing Pepper Force and Motion Rolling on Ramps Magnet Movement Marble Clock Falling Objects Roller Coasters Newton s Laws The First One The Second One The Second One Again The Third One The Third One Again Waves Waves on a Slinky Waves on Tubing Sound Standing Waves Sounds in a Bottle Heavy Metal Simple Machines Inclined Planes Levers Pulleys Gears Electricity and Magnetism Static Electricity Pith Balls Induced Charge Magnets Magnets Attract Making Magnets I Making Magnets II Technology Paper Airplanes Loop Planes Racing Spools

3 BEHAVIOR OF FLUIDS--GASES AND LIQUIDS

4 Balloons What you need: 1 balloon What to do: 1. Hold an un-inflated balloon in your hand and observe it. 2. Now blow up the balloon and pinch it closed with your fingers. Donʼt tie it off. 3. Assume that air is made up of tiny particles. Explain what is going on with these particles that causes the balloon to expand when you blow into it. Write down your explanation. 4. Hold onto the balloon and let the air out of it. Write an explanation of why the balloon does what it does, based on air being made up of tiny particles. Clean-up: Throw away the balloon or, if your teacher says itʼs okay, take the balloon home with you. Do not leave the balloon around for someone else to use, as that would be a great way to spread germs.

5 Hot and Cold Water What you need: 2 clear cups or glasses, food coloring, a supply of hot and cold water. What to do: 1. Set the two cups or glasses side by side. Fill one half full of hot water and one half full of cold water. If you donʼt have any hot water available, put room temperature water in one cup or glass and add ice to the water in the other cup or glass. 2. Put one drop of food coloring in the hot water and one drop of food coloring in the cold water. Observe what happens. 3. Describe what you observed, or draw pictures of what you observed. 4. Suppose both water and food coloring are made up of tiny particles. If they are made of tiny particles, then use that to explain what the food coloring did in the hot and cold water. Clean-up: Pour the water and food coloring down a sink and rinse out the cups or glasses.

6 Gases What you need: 1 pair of safety goggles,1 small cup or dish, ammonia. CAUTION: DO NOT GET YOUR NOSE OR EYES TOO CLOSE TO AMMONIA. IT CAN CAUSE DAMAGE. What to do: 1. Put on your safety goggles. 2. Put a small amount of ammonia in the cup or dish. Notice how it smells, but do not stick your nose near it and inhale. Just stay near it and breathe normally. Leave the ammonia where it is and move to the other side of the room. Wait a few minutes and see if you can smell the ammonia. 3. Assume that ammonia is made of tiny particles and the air in the room is made of tiny particles. What do you suppose is going on that allows you to smell the ammonia all the way across the room? Clean-up: Put the cap back on the ammonia bottle, pour the ammonia that was in the dish or cup down a sink, and rinse out the dish or cup.

7 Hot Air Balloon What you need: 1 pair of safety goggles; 1 round balloon; 1 glass pop bottle (12 oz.) or glass test tube; 1 test-tube holder (if youʼre using a test tube); 1 hot plate or tea-light candle; water. What to do: 1. Put on your safety goggles. 2. Put a small amount of water in the bottom of the bottle or test tube. 3. Place the balloon over the opening of the bottle or test tube as shown in the above drawing. 4. If youʼre using a bottle, place the bottle on the hot plate and set the plate to medium heat. Watch for several minutes and observe what happens to the balloon. or 4. If youʼre using a test tube, place the test tube in the holder and hold the bottom of the tube over a lit candle for several minutes. Observe what happens. CAUTION: Take care when using open flame. Make sure your teacher knows you are doing this activity. 5. Explain why the balloon does what it does when you heat the bottle or test tube. Clean-up: Return all the materials to where you found them.

8 Rising Water What you need: 1 pair safety goggles, 1 clear, hard-plastic cup, 1 tea-light candle, 1 small, aluminum pie tin, food coloring, water, rag or paper towel. What to do: 1. Put on your safety goggles. 2. Put about a half-inch of water in the aluminum pie tin. Add one drop of food coloring and swirl or mix gently. 3. Place the candle in the center of the tin. The water should not be so deep that the candle is covered with water. 4. Light the candle. CAUTION WHEN USING OPEN FLAME. MAKE SURE YOUR TEACHER KNOWS YOU ARE DOING THIS ACTIVITY. 5. Once the candle is lit, gently place the clear, hard-plastic cup upside down over the candle and let go of it. Do not hold onto the cup. 6. Observe what happens. 7. Using what you know about particles of air, air pressure, and heating air, try to explain your observations. Clean-up: Pour excess water down a sink and return all materials to where you found them.

9 Stubborn Baggie What you need: 1 fold-top plastic baggie, 1 rubber band, 1 glass or cup. What to do: 1. Place the baggie inside the glass or cup and fold the top of the baggie over the rim of the glass or cup. 2. Secure the baggie with a rubber band. What you have should look like the following drawing. 3. Reach inside the glass or cup and grab the center of the bottom of the baggie. Pull straight up. What happens? 4. Using what you know about air particles and air pressure, try to explain your observations.

10 Elementary Science Teacher Notes

11 BEHAVIOR OF FLUIDS

12 Overview The activities in this section are intended to help the students understand various activities in terms of a particle model of matter. Research has shown that young students do better with a model of matter consisting of particles than with all the details of atoms and molecules. Of course, if some of your students understand atoms and molecules, itʼs okay to use that language with them. Physicists consider both gases and liquids to be fluids. Hence the title for this section. Gases and liquids behave a lot alike. The pressure in both gases and fluids increases the deeper you go in them. This is because of the gravitational pull of the Earth. The deeper you are in a fluid, the greater the weight of the fluid above you, which increases the pressure. And by the way, we use pressure in describing fluids. Pressure is the force exerted on an area divided by the area. The reason we use pressure in dealing with fluids is that there are so many particles involved you canʼt keep track of individual forces exerted by individual particles. Pressure is a way of describing whatʼs going on using average force exerted over a given area. Understanding air pressure and water pressure is not easy, and thatʼs compounded by the fact that many textbooks and other resources give incorrect explanations for the behavior of fluids. Youʼll get the correct ones here. Speaking of which, there are two explanation activities in this section that are intended for the entire class at once. The instructions for those activities are here in the teacher pages. The first one, What is Temperature?, should be done after all of the students have done the activity Hot and Cold Water. The second one, titled What Gases Do, can be done whenever you feel the students have done enough activities dealing with air pressure to be ready for an explanation of the behavior of gases. You should not do this activity before the students have attempted some of the air pressure activities. Students understand concepts better when they have concrete experiences on which to base their understanding.

13 between collisions) and thus decreases the pressure. Decreasing the size of the container (decreasing the volume) increases how often the particles hit the walls (less distance to travel in between collisions) and thus increases the pressure. Repeat this simulation as the students do more air pressure activities and seem to need further explanation of whatʼs going on. COMMENTS ON ACTIVITIES With the exceptions noted above, the students can do the activities in this section in any order they wish. If they do an activity prior to the whole-class simulation of gases, they likely will have difficulty providing an explanation of whatʼs going on. Thatʼs okay. Reassure the students that just gaining the hands-on experience is whatʼs important at first. The explanations will come later. Even after youʼve done the whole-class simulation, expect the students to struggle with explaining the activities. As stated above, understanding air pressure and water pressure is not easy. Balloons This is a simple activity to get the students thinking about air being composed of particles. When they blow up a balloon, they are adding air particles to the inside of the balloon. This increases the air pressure inside the balloon and, because the balloon can expand, causes the balloon to expand. As with almost all of the activities in this section, the studentsʼ explanations will depend in large part on whether or not youʼve done the whole-class simulations. Do not expect the students to use terms like pressure or temperature, or demonstrate a full understanding of pressure and temperature, if they havenʼt done the whole-class simulation.

14 Hot and Cold Water The students put food coloring into hot and cold water. The food coloring spreads out faster in the hot water. This activity works as long as there is a reasonable temperature difference in the two water samples; so hot and cold works, hot and room-temperature works, and room-temperature and cold (ice water) works. All students should do this activity before you do the whole-class simulation What is Temperature? Gases This activity demonstrates that particles of a substance can disperse throughout a room. Ammonia molecules (or particles) evaporate from the liquid to become ammonia vapor. These molecules eventually disperse throughout the room as they bump into air molecules (or particles). Watch the students carefully when theyʼre using ammonia. They should not inhale it deeply and they should NEVER mix it with bleach. Hot Air Balloon The students use either a hot plate or open flame in this activity. Decide ahead of time whether your students are mature enough to do this on their own, and act accordingly. Make sure the students NEVER heat up a glass bottle or test tube without water in the bottle or test tube. The glass could shatter and cause injury. In this activity, the students heat a bottle or a test tube with water inside and a round balloon attached. (Do not use long balloons unless you want this to turn into a sex ed lesson!) Heating the containers does two things. First, it causes water molecules to turn to water vapor, thus increasing the number of gas particles. Second, it heats the air particles and makes them move faster. Both of these things increase the pressure exerted by the gas, causing the balloon to expand. Rising Water Again, the students are using open flame, so act accordingly. The key to getting this activity to work is to let go of the hard-plastic glass as soon as you put it upside down over the flame. If done correctly, the water in the pie tin will move up into the glass as

15 soon as the candle goes out. So, whatʼs going on? When you put the glass upside down over the flame, two things are happening. There are fewer gas particles around the flame than in the room-temperature atmosphere because you have made these particles move faster (because of the flame) and push harder on the surrounding air particles. Thus, the air near the flame is less dense. This tends to reduce the air pressure near the flame. The second thing thatʼs happening is that the flame is still heating up the air around it, causing the air particles to move faster. This increases the air pressure inside the upside-down glass. These two factors balance each other, and nothing much happens. Then the flame goes out (due to lack of oxygen inside the glass). Now you are no longer heating the air inside the glass, but you have fewer air particles per volume inside the glass than outside (remember, you heated the air before putting the glass over the flame). This results in a lower pressure inside the glass than outside the glass. The greater pressure outside pushes the water up into the glass. There is a third thing at work here. Thereʼs a chemical reaction (the burning of the candle) going on. This can result in a change in the number of gas particles inside the glass and can affect pressure, but this effect is much less important than the change in pressure due to the other factors. Stubborn Baggie As long as the rubber band makes a tight seal, the students will find it impossible to pull the center of the baggie out of the glass or cup. Prior to pulling up on the center of the baggie, the air pressure inside the cup is the same as the air pressure outside the cup. Nothing goes anywhere. When you pull up on the center of the baggie, that increases the amount of volume available to the air inside the cup. As explained in the whole-class simulation, increasing the volume available to a gas decreases the pressure the gas exerts (particles have to travel farther to hit the walls, so they hit the walls less often, resulting in a lower pressure). The more you pull, the lower the pressure inside the cup. In short order, the difference in pressure between the outside of the cup (standard atmospheric pressure) and the inside of the cup is too great to overcome with your pull. The baggie wonʼt go any farther.