Steve, good for you. It is great that you have a club to help you out. I'll keep my fingers crossed for you to get into the TI-1 program. It is fantastic! I am not sure who will be teaching it this year but it really doesn't matter, they are all great instructors.
I don't have a station up at my school yet. I am dragging my personal equipment to the school to operate. I am preparing a station grant now and hope to send it in sometime in the next two weeks. My kiddos are in the process of building some tape measure Yagis. I have a 15mw Fox transmitter so we are going to do some Fox Hunting and I may incorporate some GPS geocaching as well. I am still working on the details in my own mind but I see them doing a math problem to get the longitude and latitude of the next clue. After a couple of those the final clue will be the frequency for the transmitter. We'll see how it goes. I think the kids will love it and getting them outside will be good. I teach middle school, by the way.
Get your third graders into Morse Code. They are at a good age to learn it and will think it is cool to be able to talk in a secret code. Have fun with it and don't hesitate to let the 4th and 5th graders get involved as well. After all, it is only time and money and I know as a teacher you have plenty of both.
Anyway, good look with your club and your application. One last thing, if you didn't already know, the ARRL has brought up a teacher forum on the web site. It is a place where teachers can share questions, ideas, and classroom activities.