In honor of my birthday (yesterday), I'm going to tell you about one of my favorite activities I learned about during my job at a science museum. It involves two of my favorite things - the sun and chocolate - a perfect combination. Plus, it's environmentally friendly - what could be better?
- Cardboard pizza box (the kind delivered pizza comes in)
- Aluminum foil
- Clear tape
- Plastic wrap or heavy-duty/freezer zip-lock bag
- Black construction paper
- Ruler or stick
- Chocolate chip cookie dough
Take the pizza box and cut a flap in the lid by cutting along three sides, leaving about an inch around the sides of the flap. Fold this flap up so that it stands up when the rest of the lid is closed.
Tightly wrap the aluminum foil around the flap, tape it to the back (outer side) of the flap. Make sure to cover the inner side of the flap with the foil to reflect the sun's rays.
Place double layer of plastic wrap over the opening you made when you cut the flap in the lid, leaving about an inch of plastic overlapping the sides. Tape each side down securely, sealing out the air. If you use a plastic bag instead of plastic wrap, cut out a square big enough to cover the opening, and tape one layer over it. You want to create an airtight window for sunlight to enter into the box.
Line the bottom of the box with black construction paper, which will absorb the heat. The black surface is where you will set your food to cook. To insulate your oven so it holds in more heat, roll up sheets of newspaper and place them on the bottom of the box, forming a border around the cooking area, and tape them down. You should still be able to close the lid, but inside there is a seal so air cannot escape.
It is best to use your solar oven when the sun is high overhead - from 11 am to 3 pm. Take it outside to a sunny spot and adjust the flap until the most sunlight possible is reflecting off the aluminum foil and onto the plastic-covered window. Use a ruler or stick to prop the flap at the right angle. You can also angle the entire box by using a rolled up towel.
Now for the best part... place the cookie dough in the center of the black paper so the cookies can be seen through the hole made by the flap. Make sure the shadow from the flap is directly behind the box for the best result. Remember to move the box every couple of hours to keep up with the movement of the sun. After 4-6 hours, your cookies should be done and ready to eat, straight from your new solar oven.
You can also make toast by buttering a slice of bread, or sprinkling cheese on it, then letting the sun do the rest, or hot dogs, nachos. If you plan on using the solar oven more than once, place your food on a clear plastic or glass plate to prevent the black paper from getting dirty.
For more details (and recipes) on this activity, go to http://www.hometrainingtools.com/build-a-solar-oven-project/a/1237/
Visit www.heifer.org/schools for more great lesson plans, experiments, and games. Or learn about how Heifer International project participants in Malawi are saving energy and resources with their own environmentally friendly cooking stoves.