There are not as many resources related to star clusters and variable stars as there are resources covering topics from previous lessons, but here are a few:
- At Amazing Space, there is a graphic organizer of the differences between open and globular clusters.
- If you are looking for research projects for students, the American Association of Variable Star Observers (AAVSO) has been using amateur and student astronomers to study variable stars for many years. They can have you up and running observing a variable star very quickly, and they provide you with a lot of background content information.
- At YouTube, Phil Plait's Crash Course Astronomy series has an episode on star clusters.