APPLETS
Here are some cool applets to give a better understanding. Have fun! bcs.whfreeman.com/webpub/statistics/discostat3e/applets/DiscoStat3e_Applets.html
Go here for Best Fit Line, Least-Squares Regression
http://phet.colorado.edu/sims/html/least-squares-regression/latest/least-squares-regression_en.html