http://help.explorelearning.com/2005/05/fraction_sense_.html is a great way to show students what a fraction is and how to compare two fractions using the Least Common Denominator. This simulation visually shows the difference between how large two fractions are while showing the process of how the answer, of which fraction is larger, is received. The simulation is easily understood and I think most students would understand fractions better if they are shown Fraction Sense, while using help. explorelearning.com, when fractions are introduced to them.