Hi, my name is Becca and I hate physics.
I passed one semester of physics in college to get my biology degree and never looked back. But now that I’m teaching some astronomy, I have to understand some physics in order to teach the big bang theory and stars. Enter: the electromagnetic spectrum. For years I avoided it like the plague. I get the basics of wavelength and energy, but if you ask me to explain how a remote control works… not happening. But now that I’m having to teach it, I was forced to understand it in a way that made sense to me.
Unless you are a physicist, you are probably like me- someone who likes things that are tangible. I can understand atoms and cells because they are matter. Once you start talking about non-matter (like photons) my eyes start to glaze over. After lots of studying, YouTube videos, and help from my physics teacher friends, I finally realized that the only way for the EM spectrum to make sense for me is to think of it in terms of chemistry, not physics. I can understand it from the perspective of ionizing and non-ionizing energy.
Most students know that atoms gain energy (and vibrate faster) if they are heated. And even though most of my students have not taken chemistry, they know the basics of orbitals, and can understand the concept of electrons jumping energy levels. Atoms can release this extra energy in the form of light. We can analyze that light in space to learn things like: what elements a star is made of, its temperature and density, and the motion of the star or galaxy.
EM Spectrum Teaching Resources
1. Before you dive into the entire spectrum, start with the basics. What is radiation? Most students have heard of the term before, and have probably learned about conduction, convection, and radiation in middle school. It’s time to refresh their memory.
Grab a radiometer (ask your physics teacher for one, or snag one on Amazon) and ask students how you can get it to spin without touching it. See what they come up with before bringing out the flashlight.
2. Next baby step- What is light? Technically all wavelengths on the EM spectrum are “light” (photons), but we can only see a small portion. Light is both a wave and a particle (remember I’m a biologist, so don’t ask me to go into detail here) but we focused on waves. I had students use this PHET simulation to understand how waves move. I like how it shows water, sound, and light and students can compare the three. When they reach the light portion of this simulation, have them notice the wavelengths of different colors (red vs blue) that will be important when you get to redshift and blueshift.
3. Next baby step- Introduce the electromagnetic spectrum. What are the different wavelengths of radiation and how are they used in our every day life? I have a PowerPoint and task card review activity that are part of this bundle found on my website or on TpT.
When I was doing my background research on this topic, I also found this NASA website to be super helpful.
5. How do we use spectroscopy in astronomy? Remind students that the only way we can study space without traveling out there is by analyzing light. Each element has its own spectral fingerprint, and we can use that information to learn what stars are made of, how they are moving, and their temperature.
It’s time to bust out the spectroscopes (if you have them). Have students look at different types of light and spectral tubes and draw the fingerprint pattern they see. If you don’t have spectral tubes you could check out this java flame test virtual lab that shows the spectral fingerprint at the top of each molecule. You might also find this NASA lesson plan helpful.
6. Now that students understand different parts of the spectrum, you can show them how various NASA telescopes look at different wavelengths of light. If students head to webbcompare.com they can compare images taken from Hubble and the JWST and see how they differ. I created a fillable powerpoint that students can work on as they compare the images. You can download it free here.
Once students understand the EM spectrum, next you can introduce the big bang theory and talk about redshift as evidence of the big bang. You can find all my spectroscopy lessons bundled on my website or on TpT.
I hope that helps you non-physics teachers!