Many students struggle with understanding the relationship of brightness and temperature on the HR diagram and this activity is a great collaborative activity to help solidify this often difficult concept.
In the PowerPoint are 34 questions (listed first) that describe the many different stars on the HR diagram. Print them out, 6 to a page on a colored paper, giving each team a different color. I did 6 different colors so their were 6 teams of 3 students. The second half of the powerpoint are the answers, which you can either also have cut out and have them match it OR (what I did) is have the students run up with the description card and verbally tell you the answer. Since many of the star names are funny sounding, that makes it for a fun time. If you do it that way, just copy the words (still in order) to a piece of paper and have that next to you as students run up with their answers. If they get the answer correct, they put that descriptor in a pile or bag in front of you and the first team to complete it first wins!
The last slide has a copy of the HR diagram I gave my students to use to figure out the stars correctly.