Upper body workouts during lower body injury

I’m a teacher - one of my students, a talented soccer player, sustained an injury in his ankle - essentially a serious bruising of the bone. He’s got great care and support and is off his foot for a few weeks. We were chatting and I mentioned the idea of maybe doing some upper body training if and when he feels ready - more to keep from going crazy instead of really trying to realize gains.

Can anyone suggest a resource or two that I could point him towards? I think he might just enjoy reading about different strength training options for this sort of situation. Or even a book instead of a web guide?