The Reasons for Seasons Experiment

Tic Tac Time

Nothing is more fun on a rainy summer day than a science experiment at home! The following exercises will allow children to conceptualize the reasons for seasons in a hands-on manner. They will learn to distinguish between the Northern and Southern hemispheres and will come to understand that seasons are caused by the angle at which the suns’ rays hit the earth. This experiment has been adapted for use at home but can easily be adjusted to suit a classroom setting. You will need at least three people to complete it.

 Materials 

  • Inflatable globe or regular beach ball
  • Straw
  • Ruler & Tape
  • Protractor
  • Table Lamp (high-intensity bulb) or heat lamp
  • Yellow Bristol board
  • Thermometer (optional)

Time

1 hour

Preparation

  • Inflate the beach ball, and lay out all of the materials on a table
  • If you find that the equator line is not prominent enough, darken it with a marker
  • Cut out the shape of a sun on the yellow cardboard
  • Cut the straw in half

Part 1

This part of the experiment will focus on familiarizing children with basic terminology, the shape of the earth, and the names of important areas.

Procedure

Have children observe the globe. To be sure that they understand the shape of the earth, use the following discussion prompts:

  • Describe the way the earth looks.
  • What shape do you think the earth has?
  • Do you know what a sphere is?

Point out and define the following items on the globe:

  • Equator
  • North Pole
  • South Pole
  • Northern Hemisphere
  • Southern Hemisphere
  • Tropic of Cancer
  • Tropic of Capricorn
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Part 2

This part of the experiment will focus on ensuring that children conceptualize the earth’s rotation around the sun, its tilt, and its position in relation to the sun during each season.

Procedure
  • Create a prominent axis on your globe by fastening the halves of the straw to the North and South Poles
  • Measure the earth’s tilt of 23.5 degrees using a protractor
  • Invite a child to play the role of the sun
  • The sun will stand still as the parent rotates around them holding the earth on its axis. The parent will show the positioning of the Northern Hemisphere of the earth during winter, spring, summer, and autumn. The parent will explain that the seasons are opposite in the Southern Hemisphere.
  • Be sure to note that the earth’s orbit around the sun is elliptical and not circular. Share the fact that the earth is actually closer to the sun during the Northern Hemisphere’s winter. This helps squash the idea that the seasons have to do with the earth’s proximity to the sun.
  • To reinforce this new knowledge, invite the child to explain the earth’s rotation and tilt in their own words.

Part 3

This part of the experiment will focus on direct and indirect sunlight. It is important to note that areas on the globe that receive more direct sunlight will be warmer than those who receive more indirect sunlight.  

Procedure 
  • Turn on your lamp and explain that it represents the sun
  • Place the globe 30 cm away from the lamp. Be sure that the distance remains constant.
  • Tilt the globe about 23.5 cm. Have the Southern Hemisphere pointed at the light (winter in the Northern Hemisphere) and hold it in place on the table for about 5 minutes to expose it to the light.
  • Invite the child to place their hand over the equator. Does it feel hot or cold? Why?
  • Next, have the child move their hand to the center of the Northern Hemisphere. Does it feel hot or cold? Why?
  • Next, have them move their hand over the center of the Southern Hemisphere. Does it feel hot or cold? Why?
  • Finally, have them place their hand over the North Pole. Does it feel hot or cold? Why?

* A variation of Part 3 would be to use thermometers to measure the temperature on the different areas of the globe. See this video from Bill Nye the Science Guy for inspiration: https://www.youtube.com/watch?v=KUU7IyfR34o.

Extended Learning

Open up Tic Toc Time to view the 3D model of the earth’s orbit around the sun. Ask your child to summarize what they’ve learned over the course of the hour using the model.