Why is it hotter when I wear black in the summer?

This lesson started when a first grader asked me this question when we were doing a weather unit and it was a hot summer day in Southern California. Many of the best lessons are started by a student or students just being curious and asking questions.

This lesson was an example of that. I did this lesson over the period of one week. I have done this lesson twice and the kids have loved it both times. You can of course make it more complicated or even more basic depending on the abilities of your students. This lesson is also very easy in a multiage classroom because of the different challenges that the students need to address.

The first group of students presented their findings at a district school council meeting. The students were so enthusiastic (and I must admit quite cute) that the school board requested that the roof of our school be painted white to better reflect the heat in the summer time.

  • Grade level: K – 5
  • Subject areas:
    • Science, Math, Language Arts
    • Grade level standards are met in each of the subject areas for each of the grade levels.
  • Time Required: One hour a day for 5 days


  • The students will use the scientific method to discover which colors absorb heat and which colors best reflect heat.
  • Students will demonstrate how this information can be used at home and in the community.


  • Assorted color construction paper envelopes - ensure you have a black one and a white one
  • Calculators
  • Chart paper
  • Some stiff tag board or cardboard
  • Thermometers
  • Paper, pencils, crayons
  • Journals


Day one

  1. Ask students if what they wear makes a difference on how hot or cold they are. Write their answers on the whiteboard. Discuss.
  2. Have students tell you some of their favorite colors. List them on tag board and make sure that you have black and white on your list.
  3. Have students guess what color is hotter and what color is cooler. Use tally marks on the tag board to show the number of student’s guesses.
  4. Have students add up the number of votes in each color and the total number of votes.
  5. Have students figure out the percent that each color received of the total vote. They can also figure out the mean, median and the mode. (K-2 use calculators. 3-5 should not need them)
  6. Have the student write a hypothesis in a science journal or on a piece of paper.

Day two through five

  1. Using envelopes that you made out of construction paper that corresponds to the colors that the students chose, Place a thermometer inside each envelope. (K-1 you may have to tap prior knowledge and explain what a thermometer is and does.)
  2. Make a chart on tag board that looks like this:
Day of the week Color Time put in the sun Time taken out of the sun How long left in the sun Temperature before put out in the sun Temperature after one hour Difference in tempeture
Monday Blue            
Monday White            
Monday Green            
Monday Black            
Monday Yellow            
Monday Purple            
Monday Orange            
  1. Make one for each of the four days that you will gather data.
  2. Get your beginning measurement and put it on the chart.
  3. Tape the envelopes on to a piece of cardboard and place the cardboard out in the sun.
  4. After one hour take the students outside and record your data.
  5. Have the students do the math and record the data in their journals and on the chart.
  6. Discuss with the students the findings; see if any want to revise their hypothesis.Have them record their thoughts and findings in their journal or log.

Putting it all together

After all the data collection is complete, have the students graph their findings. Discuss the findings. Talk about how houses are like people. If a house is painted a dark color or has a dark roof it is just like you wearing a dark shirt on a hot summer day. It is cooler if your house, like yourself, wears a light color.

Have the students do an audit of the school and of their homes. Have the students present their findings to the school or district administration. Have the students talk to their parents about what they have discovered.

Funding for this lesson was provided by California ratepayers under the auspices of the California Public Utilities Commission.