Most of the supplies needed you will be able to find around the house or can be easily modified, and even better, several will keep them busy for a few weeks with a little observational creativity.
I think I might have to try out a couple myself - as my sons says 'You are never too old'.
Check them out at http://enews.gardeners.com/q/7fs9zTkmOizXXDjb6An3ATmnUjTXYewcaWgq0lB4tuK0eznQJIO27DifO