I had the privilege of teaching 4th-6th grade TAG (talented/gifted.) If students finished the current activity, they were invited to "choice time." Many children chose the polydrons. They were quite fascinated by this math manipulative that can be used to create any number of geometric structures. Age-wise, they are quite versatile; when my son was in public school kindergarten, his class owned a set. So if you're looking for something new to "play" with (and get a little learnin' in on the side), this might be an option to explore. Here's a free user guide.
BTW, I don't make anything from mentioning Polydrons; I just like 'em. ;)
