Solar S’Mores

This lesson developed by Reach Out!

Recommended Age Group: Early and later elementary

Guiding Question:

1. Can I use the sun instead of a bonfire to make S’Mores?

Objectives

Concepts:

• Solar energy is the energy given off by the sun.
• When light energy is absorbed by objects it is changed to heat energy.
• Dark-colored objects absorb more light and store more heat from sunlight.

Facts:

• Solar energy is often called “radiant energy.
• Solar energy is produced by nuclear fusion reactions within the sun.
• Solar energy does not pollute.

Principles:

• Dark-colored objects absorb more light and store more heat from sunlight than light-colored objects.
• Light-colored objects appear light to us because they are reflecting most of the light that hits them rather than absorbing it. Objects appear to be black when they absorb all wavelengths of light that hit them.

Skills

• Making Observations
• Making Comparisons
• Making Inferences
• Drawing Conclusions

Materials:

Every two people will need:

1. 4 graham crackers
2. 16 mini marshmallows
3. 2 plain milk chocolate candy bars
4. 8-by-11-inch glass baking pan
5. a clear glass lid for the baking pan
6. 1 thermometer

Room Preparation

This is an outdoor experiment: need to have a place in direct sunlight (no shade) and where animals won’t come by to eat the ingredients or disturb the pan! Use your thermometer to see what temperature it is outside. You need to do this experiment when it is at least 85° F. If it isn’t hot enough outside, wait for a warmer day.

Safety Precautions: none

Procedures and Activity

Introduction

Share the guiding questions:

1. Can you cook food outdoors?

2. What makes food cook or things melt outside?

3. How can and do we use the sun's energy to help us in our lives?

Welcome a discussion about “cooking” outside. Think about how we melt marshmallows over a bonfire, heat a hot dog on a stick over a fire, sear and cook the inside of a hamburger on a grill. Then think about what makes the melting, warming and cooking happen—heat.

Talk about what happens when we are in sunlight. Share how the heat from the sun can be used for cooking, melting and warming food.

May also share ideas and experiences with solar cooking, solar heating, and solar-powered cars.

Activity

1. Put four graham crackers side by side in the bottom of the glass baking pan.
2. Place a chocolate bar on top of two of the graham crackers.
3. Put 8 mini-marshmallows on top of the other two graham crackers.
4. Cover the baking pan with the clear glass lid.
5. Put the pan out in an area where it will get full sunlight—no shade!
6. Let the pan just sit there until the chocolate bars and marshmallows melt.
7. To make a S’More, put one chocolate and one marshmallow graham cracker together to make a sandwich. You should have two sandwiches. Enjoy!

Closing - Original Question

Were we able to make S’Mores using sun energy instead of a bonfire? Talk about what really happened. Review how the sun gives off radiant energy. Share ideas about the ways in which objects absorb light energy and it is changed into heat energy. Talk about dark colors and objects and how they absorb and store more heat.

More Ideas

1. Read about NASA’s idea of Solar S’Mores. As a result of the solar maximum, Earth’s atmosphere [was, when we originally wrote this in 2000] “puffed up” like a marshmallow over a campfire, leading to extra drag on Earth-orbiting satellites.

2. Another Experiment and Option.
You might repeat this experiment, but this time try lining the glass baking pan with aluminum foil and black construction paper. See if the marshmallows and chocolate melt faster than they did in the plain glass pan. If our hunch is right, and dark paper absorbs more sunlight and heat, we should find out the S’Mores melt faster than in the plain glass pan.

3. Or try putting the two halves of the S’More sandwiches together before you put the dish out in the sun. See what happens. Does it take longer for the marshmallows and chocolate to melt? Why? It may be that the top graham cracker is sort of like a roof of a house. It shades the chocolate and marshmallow inside. This means that it will take longer for things to melt because the top graham cracker is absorbing much of the sun’s heat.

4. Have you noticed how different the temperature can be on a hot day when you are standing right out in the direct sun instead of standing under the shade of a tree or awning? People who have houses that are under lots of shady trees will find that their homes stay cooler on hot days than those sitting out in the direct sun. Farmers are careful to be sure that their animals have shady areas available, too, on hot summer days. Can you think of other times when we use what we know about the sun and shade to help us out?

5. Check out information about the University of Michigan’s Solar Car Team. Or, try making pizza box solar ovens!

6. Explore people in your community who are using solar energy or are developing and selling products that use solar energy. Invite them to come and share their research and products.

7. How do we apply what we know about dark colors absorbing and storing more solar heat than light ones? Think about houses and buildings in hot and desert kinds of places. Often, people use stucco and light colors so less heat from the sun is stored. When you go outside on a cold and sunny winter’s day, you will be warmer if you wear darker clothing because it will absorb more sunlight. Or, on hot and sunny summer days, we are smart to wear light-colored clothing outdoors.

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Prerequisite Vocabulary

Absorb
In this case, the action of an object or material taking in energy, as a paper towel takes in water when it contacts a puddle. The marshmallows and chocolate bars take in energy from the sun.
Energy
A source of usable power