I don't have a particular video for you tonight. Instead I want you to read through the textbook section 6-1. As you read through, you can also try looking up videos at my.hrw.com (if you have a login for your history class you should be able to use the same login to access the math book, if you've had multiple logins to the site different years, try both.)
On HRW if you navigate to chapter 6, you can find some videos there. You are not required to watch the videos, you are required to pass the quiz on the right, and know the rest of the content from the section. THE QUIZ DOES NOT COVER THE WHOLE SECTION!!! So don't just do the quiz and think you know enough.
If you are checking this early, be sure to come back later and look for the quiz.