N, another thing he might enjoy is robotics. Lego robotics can be a bit pricey, but our ds loved them when he was younger. I don't know if your ds is quite ready for the actual Mindstorms series yet, but I think they have a younger version available now... and our ds might have been programming Mindstorms at 6, I just really don't remember that far back!
Our ds also spent a ton of time building things out of Legos and K'nex.
I also suspect there are a lot of cool apps out there for young kids - unfortunately for my gang the iPad came along a little after this stage of their lives, so I don't have any great recommendations for apps. I think you might find some just by googling "STEM apps for elementary" etc or searching in the app store.
polarbear
