Monday, April 6, 2009

Solar S'mores - Pizza Box Solar Oven

We finally had a sunny day in Montana! Okay, yesterday was sunny too, but we didn't realize how nice it was turning out to be until it was a little too late to begin building our oven. Today, we were prepared.

We used a box from an old science kit (from back in the days when we still bought science kits instead of making them ourselves), that was shaped much like a pizza box. Our other supplies were:

  • non-toxic glue

  • tape (regular clear tape, and packing tape)

  • scissors

  • a ruler

  • a razor knife

  • two pieces of black construction paper

  • aluminium foil

  • a 10'' x 8'' piece of glass from an old picture frame (we didn't hurt the glass, it can be put back into the frame when we are done)

  • a pen

  • two bendy straws

  • two Easy Bake Oven pans

  • graham crackers, chocolate chips and marshmallows for s'mores

We started by setting the piece of glass in the middle of the closed box lid. We traced around the glass, and then set it aside. Using a ruler we drew an additional line about 1/2 an inch in from our traced line on the side facing the front of the box, and the two outer sides. We used the a razor knife to cut along our three lines, and then lifted up our new lid within a lid (see the picture at the top of this post).

We glued a sheet of tinfoil to the inside of our new lid, being careful to keep it as smooth as possible. Then we opened the original lid of the box, and glued a sheet of tinfoil to the bottom of the inside of the box. Here again, we were careful to keep it as smooth as possible. Next we covered the tinfoil inside the box with black construction paper, and taped it in place with clear tape along the edge.

With the box closed, but our new lid open, we placed the piece of glass over the opening in the original lid, snugging it up tight against the new lid in the back. We used packing tape to secure the glass in place (I'm not sure if packing tape gives off toxic fumes when heated, but since it was on the outside of the oven, we only worried about that a little).

Finally, we used the bendy straws to hold open the foil covered portion of the lid. We discussed briefly how the foil reflects the sun into the oven. The glass allows the light to enter, and helps trap the heat inside. The foil again reflects the light, and the black paper absorbs the heat.

Once our box was ready, we prepared two test s'mores (one for my son, who was the chief builder on this project, and one for me, his assistant) in our easy bake oven pans. We placed the graham crackers in the pan, lined up sixteen chocolate chips on each cracker, and topped them with the marshmallows. Then, we popped them into our oven, and placed it on the deck at about 9:30 a.m. - it was 29 degrees Fahrenheit outside. We waited a couple of hours, they might have been done sooner, but we didn't want to chance it. Then we pulled them out, topped them with another cracker, and ate them. They were perfect! The rest of the children ate chocolate chip cookies that I made while we were waiting for the s'mores - so no one was too sad.

It was an interesting exercise. Of course, we'd like to be able to do more than melt things - we can already do that in the microwave - and a lot faster too! However, there's something attractive about harnessing the energy that's already surrounding us. We'll definitely have to take a further look at this one. Besides, I promised the rest of the children they could make their own solar s'mores tomorrow.

It's great to be a homeschooler.

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