In Brandon’s class the students were learning about light and the Doppler Effect. How objects in space that emit light will have the wavelengths of light stretched if they are moving away from the observer or compressed if they are moving toward the observer. This will change the frequency of the waves and therefore the color of light observed to a degree. Stretched will make the color more red (red has longer wavelengths) and compressed will make the color more blue (blue has shorter wavelengths).
So Brandon was showing the students spectral lines. That when you pass energy through a tube of gas of a certain element you can see the spectral lines if you use a spectroscope to break the light into the spectrum. Brandon gave each student a pair of spectroscope glasses to keep as their own and they got to look at spectral lines of different elements and talk about redshift, blueshift, and the expanding universe! :)