So this is more of a long term idea for you (not specific to what you're looking for at the moment), but it would be heavy on the science / engineering side of STEAM and might satiate his interest outside of class.
If he likes to build with LEGOs, he may enjoy the Junior FIRST LEGO Leagues. I just started a team for my kid (who is 7) with some of his friends. You build a model robot and then create a poster describing your model so that you can share it with others. It looks like a fun experience.
While the age range for the program is 6-9 year olds, FIRST considers the 6 part of the range to be "soft," meaning that if you have a kid who would enjoy the program and they are under 6, it's fine. All you would need is 1 additional kid and 1 additional adult to form a team. Or you could do something less formal but model the experience after Jr. FLL.
Last edited by George C; 10/22/15 07:20 AM.