My kids are gymnasts. They do handstands, head stands and presses to strengthen their core as well as push ups and planks.

Pilates, see if YouTube has them for kids. And I second the plank recommendation.

Planks! My kids think they are fun... little weirdos.

If he's slouching, put him in ballet.

Can anyone recommend a core workout for kids what we can do at home? Something on youtube would be great. DC is slouching in class and would like to give him more core strength. Thanks!