Use these experiments to learn more about energy and water
Build a better baker: Using the sun’s energy to cook
Objective
- To build awareness of solar energy by observing and comparing how well different solar ovens bake apple slices.
Materials
- Apple slices
- Four paper cups
- Aluminium foil
- Unwaxed white paper
- Black paper
- Plastic food wrap
- Scissors
- Tape
- Newspaper
Procedure
- Line the inside of two paper cups with black paper.
- Place a slice of apple in each cup.
- Cover the cups tightly with plastic food wrap.
- Make two large cones with paper and tape one with white paper lined with aluminum foil and one with white paper only.
- Place an apple cup inside each cone.
- Place each cone inside a second cup to hold the cooker together.
- Aim the cookers at the sun.
- Crumple newspapers around the bases of the outside cups.
- When the apples look cooked, taste to see which cooker was the best apple baker.
Other ideas to explore
- Repeat the experiment with other foods, such as potatoes.
- Try the experiment using mylar instead of aluminum foil.
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Keeping Cool Activity One: Evaporation
Objective
- To discover how much cooler water gets if we speed up the evaporative process.
Material
- Three flat pans (aluminum pie pans work well)
- Fan
- Newspapers
- Edible oil
- Warm (40° – 50° C) water
- Three thermometers
Procedure
- Put newspapers underneath pans for insulation.
- Put a thermometer and equal amount of warm water in all three pans (you need enough water to cover the thermometers).
- Let the fan blow across pan #1 only.
- Add a few drops of oil to pan #2 only.
- Do nothing to pan #3.
Discussion Points
- Which pan is coolest?
- What is the purpose of the oil?
- How much liquid is left in each pan?
- How could you use this idea to keep things cool on a hot or humid day?
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Keeping Cool Activity Two: Insulation
Objective
- To make a container that will keep ice from melting.
Material
- Uniformly sized ice cubes
- Small plastic bags
- Assortment of materials to make ice cube boxes (foil, plastic foam cups, plastic foam chips, tin cans, plastic cups, fiberglass, foam, newspaper, fabric scraps, etc.)
- Various types of insulating materials
- Metric measuring cup
Procedure
- Build a container large enough to hold one ice cube in a plastic bag.
- After one hour or longer, open the containers.
- Measure the water in the bags.
Discussion Points
- What types of materials were the best insulators?
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Understanding Why Coal Burns
Objective
- Collect methane gas from coal.
Material
- One-half cup of soft or bituminous coal
- Hammer
- Funnel
- Quart-size glass jar
- Water
- Test tube
- Rubber band
Procedure
- Hammer the coal into a coarse powder.
- Place your finger in the small end of the funnel and pour the coal into the large end of the funnel, keeping the coal in the funnel with your finger.
- Turn the jar upside-down, and place it over the funnel.
- While holding the funnel tight against the bottom of the jar, turn the jar upright and place it on a table.
- Remove your finger and slowly fill the jar with water until the funnel is completely covered, being careful not to wash the coal out of the funnel.
- Then fill the test tube with water and place it upside-down over the small end of the funnel, being careful not to let any air into the test tube.
- Mark the water line on the test tube with the rubber band.
- Observe the test tube over a two- to three-day period as it fills with methane gas.
Discussion Points
- After the tube seems to be filled, will the coal continue to give off methane gas?
- How can you tell?
- Will the methane gas you collected burn?
- Remove the test tube and put your thumb over the top. Light a match and turn the test tube upright. Holding the match above the test tube, remove your thumb and observe what happens.
- What is one reason coal mining can be a dangerous occupation?
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Tapping the Sun to Clean the Water
Objective
- Determine how much clean water can be extracted from muddy water through evaporation.
Material
- Large cooking pot
- Drinking glass
- Clear plastic food wrap
- Masking tape
- Two rocks
- Muddy water
Procedure
- Fill the pot to a depth of five centimeters with muddy water.
- Place the drinking glass right-side-up in the middle of the pot, placing a rock in the glass to keep it from floating, if necessary.
- Cover the pot with the clear plastic food wrap and tape it firmly to the pot.
- Place a rock on the plastic wrap to make it sag in the middle, but don’t let the plastic wrap touch the glass.
- Place the pot in direct sunlight for several hours.
Discussion Points
- Why did tiny droplets of water appear on the cool plastic wrap?
- Why did they fall into the drinking glass?
- Is this a good way for your community to get pure drinking water?
- From this experiment, does it look like mud evaporates?
Additional Activities
Try this experiment with salty water. Also determine how clean your evaporated water is by placing several drops in a drinking glass and allowing it to evaporate. Do the same with several drops of muddy or salty water. Observe any residue left in the glasses after the clean, muddy or salty water evaporates.
Additional Discussion Points
Do you get more clean water from salty water or muddy water?
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