Published: April 13, 2016

Sunshine S’mores

Drawing of a s'more, a sandwich of a marshmallow and a square of chocolate between two graham crackers.


A solar oven is a box that traps some of the Sun’s energy to make the air inside the box hotter than the air outside the box. In other words, the solar oven is like a super greenhouse.

Photo of solar oven to make in this activity.

You will need:

  • Cardboard box with attached lid. Lid should have flaps so that the box can be closed tightly. Box should be at least 3 inches deep and big enough to set a pie tin inside.
  • Aluminum foil
  • Clear plastic wrap
  • Glue stick
  • Tape (transparent tape, duct tape, masking tape, or whatever you have)
  • Stick (about 1 foot long) to prop open reflector flap. (Use a skewer, knitting needle, ruler, or whatever you have.)
  • Ruler or straight-edge
  • Box cutter or Xacto knife (with adult help, please!)

How to make solar oven:


Have an adult cut the box with the box cutter or blade.

Using the straight edge as a guide, cut a three-sided flap out of the top of the box, leaving at least a 1-inch border around the three sides.

Drawing shows where to cut the flap in the lid of the box.

Cover the bottom (inside) of the flap with aluminum foil, spreading a coat of glue from the glue stick onto the cardboard first and making the foil as smooth as possible.

Line the inside of the box with aluminum foil, again gluing it down and making it as smooth as possible.

Drawing shows box lined with foil and foil on bottom side of flap.

Tape two layers of plastic wrap across the opening you cut in the lid—one layer on the top and one layer on the bottom side of the lid.

Drawing shows box with plastic wrap taped across opening of box.

Test the stick you will use to prop the lid up. You may have to use tape or figure another way to make the stick stay put.

Put the oven to work

Set the oven in the direct Sun, with the flap propped to reflect the light into the box. You will probably have to tape the prop in place. Preheat the oven for at least 30 minutes.

To make S’mores, you will need:

  • Graham crackers
  • Large marshmallows
  • Plain chocolate bars (thin)
  • Aluminum pie pan
  • Napkins!

Break graham crackers in half to make squares. Place four squares in the pie pan. Place a marshmallow on each.


Note that unlike most recipes, our s’mores have the marshmallow UNDER the chocolate. That’s because, in the solar oven, it takes the marshmallow longer to melt than the chocolate.

Place the pan in the preheated solar oven.

Close the oven lid (the part with the plastic wrap on it) tightly, and prop up the flap to reflect the sunlight into the box.

Drawing shows completed solar oven, with pan of graham crackers with marshmallows only on top.

Depending on how hot the day is, and how directly the sunlight shines on the oven, the marshmallows will take 30 to 60 minutes to get squishy when you poke them.

Then, open the oven lid and place a piece of chocolate (about half the size of the graham cracker square) on top of each marshmallow. Place another graham cracker square on top of the chocolate and press down gently to squash the marshmallow.

Close the lid of the solar oven and let the Sun heat it up for a few minutes more, just to melt the chocolate a bit.