Students test whether the color of a materials affects how much heat it absorbs. Students will place an ice cube in a box made of colored paper (one box per color; white, yellow, red and black), which they will place in the sun. The students will make prediction as to which color will melt the ice cube first. They will record the order and time required for the ice cubes to melt. This activity can be done independently or in conjuction with both a math and/or science lesson. A discussion and journal-writing period can follow. For a more challenging activity, a discussion about solar energy can be included.
LEVEL OF DIFFICULTY [1 = Least Difficult : 5 = Most Difficult]
60 minutes (1-2 class periods)
Less than $10 per class
WHAT WILL THE STUDENTS LEARN?
1.1 Identify and describe characteristics of natural (e.g. wood, rocks, wool) and human-made materials (e.g. Styrofoam, plastic, fabric).
1.2 Identify some possible uses and advantages for natural and human-made materials.
Certain colors absorb light better than othersBACKGROUND INFORMATION:
The sun produces heat and light
Why ice cubes melt
The purpose of solar panels
SOLAR ENERGY: energy derived from sunlight
SOLAR CELL: a photo-electric cell that converts sunlight directly into electrical energy and can be used as a power source
SOLAR PANEL: a group of solar cells forming a flat surface (as on a spacecraft)
HEAT: a form of energy that causes substances to rise in temperature or to go through associated phase changes (as melting, evaporation, or expansion)
ENERGY: the capacity for doing work; raising weight, for example.
ABSORB: to take in; to transform (radiant energy) into a different form usually with a resulting rise in temperature
REFLECT: to bounce waves of light, sound, or heat off a surface
RADIANT ENERGY: energy (as heat waves, light waves, radio waves, X rays) transmitted in the form of electromagnetic waves
MELTING: (in terms of an ice cube)
The sun emits energy in the form of electromagnetic waves. We see part of the electromagnetic wave as light and we feel part of it as warmth. Darker colors absorb more sunlight than lighter colors, which is why darker colors get warmer more quickly in the sunlight than lighter colors. The lighter colors reflect more of the sun's radiant energy, so they remain cooler to touch in the sunlight.
http://newton.dep.anl.gov/askasci/gen99/gen99540.htm - Answers the question of why different colors absorb more or less heat
http://newton.dep.anl.gov/askasci/phy00/phy00156.htm - Further explanation of heat absorption and different colors
4 sheets of colored paper per group (white, yellow, red, black)PREPARATION:
Scissors (1per student if you want the class to cut out the boxes)
4 ice cubes per group
sunny day or a heat lamp
Make enough ice cubes so that each group can have four. Try to make them the same size so that the experiment is consistent.
Cut out the colored paper into 5 sided boxes big enough to fit the ice cube for each group. To save class time tape the boxes together, or if time is availible have the students cut, fold and tape their own boxes together.
Obtain the rest of the materials.
Photocopy one chart per group (see link).
For shorter lesson, precut and assemble colored boxes
1. Ask them to imagine that it is 100-degrees outside. What kinds of things will they do to stay cool? What kinds of clothing will they wear? Any thought to color? Once the class is thinking about the influence of color and its relationship to heat.
2. Divide the class into small groups.
3a. For a shorter lesson have the colored boxes pre-cut and assembled and hand out one of each color for each group of students.
3b. For a more involved activity give each group 4 sheets of colored paper (white, yellow, red, black) and have them cut and fold thier sheet into a box.
4. Hand out newspaper and have each group spread the newspaper under the heat lamp or in a sunny place outside.
5. On the newspaper, place the boxes side by side with the opening facing away from the sun/light so the students can see inside.
6. Give each group 4 ice cubes and instruct them to place 1 ice cube in the center of each colored cube.
7. Let the ice cubes sit in the sun until they have melted. Have the students check on them every few minutes and record which ice cubes melted first, second, third, and fourth.
8. Instruct each group to record their data on the chart (see link).
9. Discuss with the class their observations, touching on the different colors and their ability to reflect light and heat. Also talk about how these characteristics of color help to melt the ice.
Why do ice cubes melt?REFERENCES:
How does the sun affect ice?
What kind of clothes do people wear outside in the winter/summer?
On which color did the first ice cube completely melt? Why?
If an ice cube was placed on a blue piece of paper, how much time do you think it would take to completely melt?
Which color absorbs heat the quickest in the sun?
Which color would be the best to help keep ice cubes from melting too quickly in the sun?
FOR A MORE CHALLENGING ACTIVITY: a discussion of solar panels and solar energy could be included. Also, discuss heat as a form of energy.
Richards, Roy. An Early Start to Technology from Science. London: Simon & Schuster, 1990, page 64.
See Associated Download.
See Associated Download.