An Investigation in Earth Systems
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Leo 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?”
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.
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 https://science.nasa.gov
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.
Ways of demonstrating ultraviolet light:
- UV beads
- Black lights
Ways of demonstrating visible light
- vis spectrometer
- prism glasses.
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 have the longest wavelengths in the electromagnetic spectrum.
Ways of demonstrating radio waves:
- Cell phone
- Walkie talkie
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.
- Light source. (Incandescent)
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
- 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.
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?
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.
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: