Using spectra – one way astronomers get important information about the chemical composition of distant objects is through their emissions spectra. Activities can be built around observing different spectra (if you have access to optical spectroscopes) or printouts of spectra from objects in our universe. Students can determine what elements are being detected and what conclusions can be drawn from this information.

Detecting exoplanets – NASA is a great resource for activity ideas related to detecting exoplanets. They have activities appropriate for every student level here.

Proxies – since we can’t get to the places that astronomers want to investigate, we have to learn as much as we can from the light that reaches earth. Have a discussion in class about what proxies are, what assumptions are behind them, and how we know they are reliable.