Solar Oven: My middle son and I did this project when he was in 4th grade.
A medium size pizza box
Black construction paper
Extra-wide aluminum foil
Clear Plastic sheeting (available at hardware or fabric stores)
Glue, Tape, Scissors
Draw a one inch border on all four sides of the top of the pizza box. Cut along three sides leaving the line along the back of the box uncut. (Diagram #1)
Form a flap by gently folding back along the uncut line to form a crease. (Diagram #2)
Cut a piece of aluminum foil to fit on the inside of the flap. Smooth out any wrinkles and glue into place. Measure a piece of plastic to fit over the opening you created by forming the flap in your pizza box. The plastic should be cut larger than the opening so that it can be taped to the underside of the box top. Be sure the plastic becomes a tightly sealed window so that the air cannot escape from the oven interior.
Close the pizza box top (window), and prop open the flap of the box with a wooden dowel, straw, or other device and face towards the sun. (Diagram #4) Adjust until the aluminum reflects the maximum sunlight through the window into the oven interior.
Your oven is ready! You can try heating s’mores, English muffin pizzas, or hot dogs, or even try baking cookies or biscuits. Test how hot your oven can get using a simple oven thermometer!
If you want something a little easier to try, this is one I did with my kindergarten and first grade classes.
Heavy Duty Aluminum Foil
Hershey Chocolate Bar
Instructions: Tear off a piece a 12” piece of foil. Place ½ a graham cracker in the center of the foil. Place ½ of the chocolate bar on top. Next, top with a marshmallow and the other ½ of the graham cracker. Wrap tightly and place in direct sunlight for 30 minutes. Enjoy the gooey treat. Talk to your kids about why some items melted and others did not.
Variation: Place one in the sun and one in the shade. Compare the results.
Solar Energy Kids Experiment: Ice Cubes
This solar energy kids experiment is aimed at understanding the different heat absorbing capacity of different colors backgrounds and the effect of those on the melting rate of ice cubes.
6 different colored square pieces of card or paper. Black and white are essential, and any other 4 colors will do (the three primary colors red, blue and yellow, as well as green are good choices for the other cards). Make the squares about 7cm x 7cm (3 inches x 3 inches).
6 ice cubes of the same shape and size
food coloring (optional)
Put one ice cube on each card and place them all in the sun. Make sure all the ice cubes are exposed to full sunlight. See which one melts the fastest, which melts the slowest.
What Will Happen?
The black card or ice will melt fastest as it absorbs the most light; it is the most efficient Solar heat collector. The white will melt the slowest since it reflects most of the light. The other colors absorb all the light EXCEPT the ONE they reflect; this is the color they appear to us.
Another option is to make colored ice using food coloring. For the white block I suggest adding milk to the water and for the black one mix up all the other color food dyes; it won't be quite black but it will be close enough. Other options for the black block could be cola. This variant will have a lot more interest for your child as they also get to prepare the ice. For this variation, use white paper. Combine Both Tests:
Why not combine both the colored cards and the colored ice blocks and compare the results! Both these activities together will take a young child at least an afternoon to complete. And while she's outside watching the ices melt, you might even get a break...