S'mores, a Pizza Box, and Sunlight
Updated: 2 days ago
Have you ever been camping? Maybe you were a Cub Scout, Boy Scout, Brownie or Girl Scout as a kid, or maybe your kids were, or are now? If so, you probably have fond memories of sitting around a campfire roasting marshmallows to make a delicious treat of s’mores or cooking hotdogs while talking and laughing with others. Many of your students will be able relate to cooking simple food over a campfire, but do they know that they can also cook food using a homemade solar oven? Yes, they can make solar oven in class using a pizza box.
There are actually some solar ovens specially designed for camping that you can buy online. I have never used these myself because I am not a regular camper. I have only camped a few times as an adult when my son was in Cub Scouts, and when I was little, I went on some camp outs as a Brownie. If I were a regular camper, maybe I would purchase one.
For this homemade, in-class solar powered oven, your students will use a clean, empty pizza box to build their own solar powered oven to cook s’mores. If any of your students are allergic to wheat or gluten, you can ask them to bring in gluten free graham crackers on the day of the “cooking”. If anyone is allergic to milk, you can leave out the chocolate in the s’mores or bring in dairy free chocolate for them.
The pizza box solar oven is a perfect addition to your lessons on types of heat transfer (conduction, convection, and radiation), as it will use all three types of heat transfer to cook food. While these are more physical science topics, the solar oven pizza box can also be incorporated into a biology unit when discussing solar energy, heat transfer in an ecosystem, or the greenhouse effect. I particularly like this lesson for 7th and 8th grade science. It is one that will certainly yield high student engagement if you can find a way to incorporate it into your lessons.
When ready to take the pizza box solar ovens outside to cook with, you will need a day where the sun is out, so be looking ahead and checking the 10-day forecast before you set the date to do the cooking portion of this activity. Try and do it on a day it is 80 degrees or higher. Make sure it is not a windy day, or you will have pizza oven boxes flying everywhere and students running trying to catch them. Now, that's a site :).
Do not choose a cloudy or overcast day either. The clouds will block and scatter the light rays that are needed to heat up the box oven. You want direct sunlight for this activity. You will only have a limited amount of time for this activity, as you will need to take roll, explain the activity, then line the class up and take them outside with their pizza box. It will be a waste to do all this and then realize once you are out there that the sun is not out, or weather is not cooperating in any kind of way, so prepare ahead and make sure the weather is just right the day you choose to do this with your students.
Prepare for the Day
Tell the students ahead of time to bring in a clean pizza box of some sort to class and write their name and class period on the bottom of it. This is a good excuse for them to ask their parents to take them out to eat pizza, tell them. They can ask an employee for one extra empty box, they might give them one at no charge. If they use a used pizza box, tell them make sure to clean it well before using. This lesson will need at least two class periods, one for building the pizza box and another one for going outside to test it out.
Materials Needed:
Clean Pizza box
Pen or pencil
Glue stick
Mini thermometers
Ruler
Black construction paper
Scissors
Plastic wrap
Aluminum foil
Strong tape
Wooden grilling skewer or a pencil
Mini aluminum pie pans
Hand sanitizer
Marshmallows
Graham crackers (Cut into little squares or rectangle pieces)
Hershey chocolate bars (broken into several pieces)
Day 1: Making the Pizza Box Solar Ovens
1. Draw a large square using a ruler on the front of the pizza box, about one inch inward from
each of the four sides.
2. Now you will begin cutting out a flap. Only leave the side of the square that is on the same
side as the hinge of the box (top of the box) uncut. Do NOT cut this side. This way when you
have cut out the other three sides, you will have created a flap in the lid that you will lift open.
3. Fold the flap back, then line the inside of this cardboard flap with aluminum foil. Then fold the
aluminum foil over the flap to hold the foil in place and tape the foil onto the outside of flap.
Smooth out the foil with your hands.
4. Cover the opening you made in the pizza box lid with plastic wrap. Attach the plastic wrap to
the opening’s edges using the clear box tape. Make sure there are no openings or holes in the
plastic wrap covering. It should be an airtight and snug covering over the square opening. If
you want it extra secure, add a second layer of plastic wrap on both sides of the opening and
tape the wrap securely on to the box. Be careful not accidently pierce the plastic wrap while
cutting it. You may find it helpful for someone to hold down the plastic wrap while you tape it.
5. Next, line the inside of the box with aluminum foil so when you close the box, the entire floor
of the box is covered with foil. Then cover around the square on the inside of the pizza box lid
(See the picture below). Tape the foil to the box so it stays better. If it is too long, cut it and tape
the foil that hangs over the edge of the box, so the foil stays in place.
6. Now, place a black sheet of construction paper to the inside of the pizza box as shown in the
picture. You may want to measure it first, then cut it to fit the box.
7. Finally, use a wooden skewer or pencil and tape to prop the lid of the solar oven. Raise it at
about a 90 degrees angle from the bottom of the box.
8.Now place half of a graham cracker on a small, folded piece of aluminum foil that is a bit bigger than the graham cracker. Place a big marshmallow and piece of a Hershey's chocolate on top of the graham cracker. You can also place the s'more on a mini pie pan if you prefer. Then put the s'more and foil bottom on (or pan) on the black construction paper that you used to line the inside of the pizza box with.
Day 2: Trying out the Solar Pizza box Ovens
Remind students of your behavior expectations for them before they go outside to test their solar ovens. Line them up with their projects and go outside. Remember to do this on a warm day, with sun out, and little to no wind. Students can put a mini theromoeter inside their pizza box ovens (next to their S'mores) to record how hot it gets in their oven and how quickly the temperature rises. They can record the temperature every 5 minutes in their science notebook. Try and be outside for about 30 minutes if your class time permits you to do so. Be sure students place their pizza box solar ovens in place that it will get full, direct sunlight, and make sure the open side of the flap of their oven faces the sun.
When the chocolate and marshmallows have softened on the graham cracker, they are ready to be eaten. You can give the students hand sanitizer to clean their hands (or they can wash their hands with soap and water) before they eat their tasty dessert. Remember to collect the mini thermometers from your students before class is over.
Science Concepts Explored in this Activity:
Light Absorption is the process where matter takes in in light energy from electromagnetic radiation. Visible light is a form of an electromagnetic wave. In the solar oven pizza box, light energy is absorbed by the black paper and changed into heat. There is reason black paper was chosen for this project as black absorbs more heat than light colors, so should get hotter. This why you should wear light colored clothes when outside during the summer when it is hot outside, rather than dark colored clothes.
Radiation is the transfer of energy through space or a medium in the form of waves or particles. In this activity, sunlight hits the aluminum foil flap, then reflects this light and directs it to inside the box. One way the s'more inside the box gets heated is through radiation.
Conduction is the transfer of heat or electrical energy through matter by direct contact between adjacent atoms, without any movement of matter. In this activity, the sun's energy heated up the black paper in the pizza box, and this heat was transferred to the foil the food was sitting on top of. Then the heat was transferred from the foil to the food. This cooks the food.
Convection is warm, less dense air naturally rising and then cooling and cool air being more dense than warm air, sinks. Convection currents inside the pizza box circulate the trapped heat which helps to cook the s'mores. The plastic wrap was used to trap in the heat.
The Greenhouse Effect is a natural warming process that happens when certain heat-trapping gases in Earth's atmosphere trap in heat and keeps it from escaping into space. This creates a blanket, in a way, which helps to maintain an average temperature on Earth that is compatible with life. In the solar oven pizza box, thermal energy is trapped inside by the tightly sealed plastic wrap and helps to cook the food. This is an example of a greenhouse effect as it allows direct and reflected sunlight to enter the box, while at the same time retains heat.
Solar Energy is a renewable energy source. Solar energy is used to cook the s'mores in this solar powered pizza box oven.
Try These Extensions
Have students try making the solar pizza box ovens using a white construction paper and see if it yields different results. See if it takes longer to melt the chocolate and marshmallow, or did it take the same amount of time as when you used a black construction paper? If they place a thermometer inside the box, have them measure the temperature differences every 5 minutes for 30 minutes. Which one gets hotter?
Try changing the angle of the pizza box lid and see if this makes any difference in this experiment.
Try setting up this same experiment on an overcast day verses a sunny day. What did you observe?
What else can you cook in it? Cheese pizza?
Can your students think of different materials they can use to insulate their solar pizza box ovens? Tell them to explain why they chose that material?
Does the size of the pizza box make a difference in how long it takes for the marshmallow and chocolate to melt? Try using a big box, like from an Amazon shipment. Line the inside completely with foil as you did with the pizza box and see if there is any difference in the time it takes to cook with s'mores. Record the temperature in both boxes and see which one gets hotter.
