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An Investigation in Earth Systems

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Teachers: Link to the PD session overviewing this activity

Leo the happy dogLeo loves to go with us when we are in the car. But in the summer we can’t always take him places because the car gets too hot sitting out in the sun. Why does the car get so hot sitting in the sun? Why does the car get hotter in the summer than in the winter?



Do a word web as a class about the question. “Why does the car get hotter in the summer than in the winter?”

Sample word web



Sample word web graphic

The word web should be teacher-guided but student-made. The reason for this is to get students thinking about the steps they need to take to learn something new.

The Unit:

Let's start with where the energy came from...

The sun gives off energy in the form of waves. These waves are part of the Electromagnetic Spectrum. They include the visible light that you can see as well as UV light, IR light, Microwave, and even gamma waves. Light waves are made of both electricity and magnetism so they are called electromagnetic waves. These waves travel about 186,000 miles (300,000 kilometers) per second. This means a beam of light could go 7 ½ times around the world in one second


Graphic from

Now that we have taught students that the different types of light energy have waves, we can explore the parts of a wave. 


This video shows how to demonstrate the part of a wave with a spring. You can just use a slinky to demonstrate this. 

Another video explaining how to use a rope or spring in the first 10 minutes of our 2020 PD video


  • A rope, spring, or slinky

We can see from the NASA graphic above that there are all types of waves included in the electromagnetic spectrum. Let's explore some of these waves. 

Ultraviolet Light

Ways of demonstrating ultraviolet light:

  • UV beads 
  •  Black lights
Visible Light

Ways of demonstrating visible light

  • vis spectrometer
  • prism glasses. 
Infrared Light

Infrared photo of person and pipes  


Ways of demonstrating infrared light:

  • IR thermometer
  • IR camera
  • TV Remote
  • IR Remote sensing

Ways of demonstrating microwave energy:

  • Cook popcorn in the microwave 
Radio waves

Radio waves have the longest wavelengths in the electromagnetic spectrum. 

Ways of demonstrating radio waves:

  • Cell phone
  • Radio
  • Walkie talkie


Wave Assessment: 

Make a poster, infographic, or commercial about a type of energy from the electromagnetic spectrum

  • Include the following
    • The type of wave
    • The wavelength of this wave band
    • The uses of this type of energy


Well, all that energy from the waves must do something! Right! Let’s look at this simple setup of a radiometer

radiometer showing indirect and direct light

Demo: Radiometers under a lamp


  • Radiometer
  • Thermometer
  • Light source. (Incandescent)
Graphic of the light from the sun hitting the Earth

The radiometer setup is a good model of how the Earth works too. We see that some of the earth gets more direct light and others get more indirect light at different times of the year. This is due to the tilt of the Earth. 


Now let’s explore what happens to that energy once it hits the Earth.

Which will warm up faster a dark cloth or a light cloth in the sun? Here is a video showing fabric warming up in the sunlight. 


  • IR Thermometer
  • White cloth
  • Black cloth

You can do this in the classroom with lights with incandescent bulbs. 


Another demonstration that shows darker materials absorb more energy than light materials.


Demo: Laser and balloons 

  • Supplies
    • Green 100 mw Laser Pointer  
    • White balloon
    • Black balloon

Now let’s look at the Earth. 

Pull up Google Earth and zoom out to see that the Earth has lighter and darker places.

Google-Earth.png Google-Earth-zoom.png

You can have students do this or do it as a class. 

Guiding students
  • Zoom in to different levels and observe the different features or structures. 
  • Are there light and dark places?
  • What do you think happens in these areas?

Convection Currents

OK, if things absorb different amounts of energy and the darker materials warm up more than the lighter materials, what does that do to the Earth?

Model Convection currents in a tank. 

Full video of the convection currents demonstration.   
Short Video of the convection currents demonstration.   

But why do convection currents work?

Density straws activity 

The Density Straws activity allows students to develop an understanding of density. This can be then used to analyze the convection current demonstration to help students understand how convection works. 

  • Student handout  NOTE: I do not give this to students before the lesson. I only use it as a scaffolding tool for groups needing a bit of help. 

Overview of greenhouse gases:



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