There's a little boy in DD1's gymnastics class (out of four students, not just the one in a huge class of girls ), and they have full classes of older boys as well there At this age, it's mostly forward rolls and climbing, so not too "girly" if that's what might scare your husband. Make him watch some male gymnasts in the Olympics, that'll show him how "manly" the sport can be!

Go with what your DS wants to do, if he's able to express an opinion. At this age they just want to move and play