A couple of students in my on-line classes have been asking questions about multiplying fractions. Should you simplify before or after multiplying? How should you simplify? By cross-canceling directly, or by a prime factorization and cross-canceling combo? Here are some videos I have made to help clarify the situation.
http://content.screencast.com/users/Mallwalker52/folders/Jing/media/595b65da-573a-4dfd-92c3-2416f129b1f5/jingswfplayer.swfView on screencast.com »
Jon Oaks 