http://handsonmath.blogspot.com/2011/03/teaching-simple-interest-choosing-best.html

Above is a link with the simple interest videos I mentioned in class for Periods 4B and 6B. Just something cute to look at.
Also if you are interested in the compound interest formula see below:
http://qrc.depaul.edu/StudyGuide2009/Notes/Savings%20Accounts/Compound%20Interest.htm

Homework: Periods 4B and 6B:
Odyssey Module E - due 1/23
Pg 333 #6-18