Hi, Tom.
I haven't had time to check the forum lately, so I am just now reading your posts about the stamp class you are starting. What wonderful news!
There are many, many resources online that you can use.
First of all, you might like to use the Boy Scout's stamp collecting merit badge program for some ideas one what to teach. A PowerPoint of all the topics they need to learn can be found here:
http://www.wfscstamps.org/Youth/Also on this page (from the Wisconsin Federation of Stamp Clubs) are club leader resources, games, activities, etc. etc.
The American Topical Association's website has a youth page with a beginner's guide and a publication called "Topical Tidbits" that focuses on a different topic each issue. These pages can be printed for free. I use a lot of these as stand alone activities with my stamp club.
There are also a few youth pages on the American First Day Cover Society's website. (Not too many, though. I do all the work for the above mentioned sites and don't have much time for the AFDSC, unfortunately!)
One thing I have found that kids love are scavenger hunts. I have made many of these that I can email you if you PM me. There are ones for Australian stamps, stamp collecting terms, the color red, etc.
Please let me know if you need anything specific. I may have it and would be glad to share.
Good luck!
Aimee