This is a differentiated assignment for high school Earth & Space science, though it could be adapted for middle school. It focuses on H-R diagrams and the life history of stars.
I love ABC assignments. They are a grade contract. I tell you what work you need to do to earn what grade. The C-level is typically easy to complete in class. To earn a B you have to do the C and B assignments. An A means you do all three, and probably have to do some work outside of class. In this case, the A-level requires doing an online simulation and writing about it.
I've posted this as a doc, so you can edit due dates, point values, etc.