For me, I need to jump topics a lot. My medication only makes it possible for me to concentrate for longer periods of time. It doesn't prevent me from getting bored and needing to do something else for a while.

I'm a musician and in my practice, I've found that I'm most effective on my off days when I spend only a few minutes on each exercise and allow myself to take frequent short breaks unless I become hyper focused. So if I were to complete a bunch of worksheets for school, I'd do math for 10 mins, then jump to English for 10 mins, get up and walk around the room for a few seconds, return to math for a few minutes and then maybe history. That style of work keeps my focus and refreshes my attention span.

I think that keeping the kid in for recess is a horrible idea. She needs to go out because there is no way that any amount of drug is going to make her be able to focus on something boring for 6 hours.