Need a physical science activity for the winter months? Here's a snowy winter activity that just can't be used in the spring!
Benjamin Franklin's First Experiment
In 1736 Benjamin Franklin followed the intellectual tradition of Sir Isaac Newton's Treatise of the Reflections, Refractions, Inflections & Colours of Light when when, in his first published experiment, he determined a relationship between color and heat.
This experiment can easily be reproduced with students on the first sunny day after the next snowfall.
Content Areas: Art, Physical Science, Math, History
Materials:
- Vocabulary Sheet
- Paper
- Crayons
- Prism
- Flashlight
- Nine foil baking pans per group
- Ruler or measuring stick
- Cloth squares of the same material (felt is inexpensive and easy to find in a variety of colors) in spectrum colors (red, orange, yellow, green, blue, indigo, violet) and black and white for each group. For a variation on the experiment provide some groups with lighter shades of the colors (pastels, for instance)
- Snow
- A sunny afternoon
Whole Class Advanced Organizer:
Distribute and discuss vocabulary sheet following terms:
- Scientific method (problem, hypothesis, process, data, conclusions)
- Color spectrum
- Prism
- Heat
- Light
- Hand out crayons. Ask students to draw a picture of the sun. Then ask what colors they chose for the sun. Ask whether anyone used purple or green in their sun. Why not?
- Turn off the lights. Shine the flashlight into the prism so that the resulting color spectrum shows clearly on a wall, screen or piece of white paper (Classroom management strategy: Practice this in advance of the actual class so that you can be sure that the spectrum is in full view of the entire class. What are the colors that the students see in the resulting rainbow?
- Now ask the class why people in desert or tropical climates wear lighter clothes (Lighter colors are cooler), and explain that darker colors absorb more light and heat while lighter colors reflect more light and heat.
- Write the following Problem Statement on the board: Which colors on the spectrum absorb more heat?
- Divide students into small groups for the purpose of creating a written hypothesis.
- Briefly share each group's hypothesis before going outside to continue with the experiment.
- Have each group collect two inches of snow in each pan. Use the measuring stick to measure the snow's depth.
- Place the pans in a row in direct sunlight. Place one square of each color in each pan.
- Check the pans every twenty minutes and jot down observations (collecting data) about how much snow has melted under each square. Ask students to take measurements of any observable difference in the snow.
- Replace the felt between each data collection.
- Allow time for the students to write up their process, data and conclusions. Ask students to illustrate their results using a graph.
- Guide students in a discussion of the results: Franklin concluded that darker colors heat faster than lighter colors. Do student bar graphs parallel Franklin's findings?
Effects of Heat on Color
Explain to students that the colors we see are a result of light that objects absorb and reflect. Whereas the white cloth reflected all or nearly all of the sunlight, the dark fabric absorbed all of the sunlight. Thus, the snow under the lighter colors should have melted the least amount, but the snow under the darker colors should have melted the most.
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