28 E Definition of subgroup+lots of examples

In this video I define subgroup and then we look at lots of examples and nonexamples of subgroups based on the groups that we are very familiar with.

This video is the first part of what we covered in class on Feb. 23, 2021. It is longer than most of the videos because I created this video to help my students who were not in class today because they were in precautionary covid isolation.