I have a great resource for you! Pete's Power Point Station is a great site for you to download interactive PowerPoints for your elementary students! It includes PPT's on science, history, math, language arts, geography, and games! There are literally hundreds of PPT's that are already created, that you can download and use for your classroom today!
Just for kicks, I wanted to relive my elementary school days and chose the painful topic of "Grammar." When I looked at the PPT's available, there were over 20 on sentence structure, using commas, capitalization, etc. When I looked through several of the PPT's, I felt depressed. If only this resource was around when I was in elementary school!
You may want to also check out this hilarious video by Don McMillan called "Life After Death By PowerPoint!"