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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

Procedure

Other ideas to explore

Apple slices

Four paper cups

Aluminum foil

Unwaxed white paper

Black paper

Plastic food wrap

Scissors

Tape

Newspaper

 

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.

 

Energy Experiments

Use these experiments to learn more about energy and water

Repeat the experiment with other foods, such as potatoes.

Try the experiment using mylar instead of aluminum foil.

Keeping Cool Activity One: Evaporation

Objective

To discover how much cooler water gets if we speed up the evaporative process.

Materials

Three flat pans (aluminum pie pans work well)

Fan

Newspapers

Edible oil

Warm (40° - 50° C) water

Three thermometers

Procedure

Discussion points

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.

 

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?

Keeping Cool Activity Two: Insulation

Objective

To make a container that will keep ice from melting.

Materials

Procedure

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

 

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?

Understanding Why Coal Burns

Objective

Collect methane gas from coal.

Materials

One-half cup of soft or bituminous coal

Hammer

Funnel

Quart-size glass jar

Water

Test tube

Rubber band

Procedure

Discussion points

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.

 

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?

 

 

 

Tapping the Sun to Clean the Water

Objective

Determine how much clean water can be extracted from muddy water through evaporation.

Materials

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?