Past Simple vs. Present Perfect
This is a powerpoint presentation which you can simply use to show the distinction between Past Simple and Present Perfect Tense. All you need is a overhead projector! Because it shows one distinction at one page, I think your students won't find it so confusing. Also you can give this worksheet to your students so that they can look at it whenever they get confused about the distinction between Past Simple and Presen Perfect.

I hope you find it useful. Enjoy it!