Probably not fruit juice, which is too high in potassium for most of those with HyperKPP and too high in sugar most of those with HypoKPP, but plain water. However HypoKPP youngsters should be drinking diet soda, not the sugar-sweetened type. This is the factor which forces many of our youngsters into home-schooling. It will be helpful if the youngster can sit in the back of the class, so they are able to get up quietly and walk as needed. The teacher can help by making use of any opportunities to send the affected student on quick errands, or by finding ways to get them out of their seat and moving a little.
Adults report that chewing gum is enough activity for some to stave off attacks.
In both cases the end result is ion imbalance and temporary paralysis. Steady, gentle activity keeps this ion imbalance from happening. So, even though gum chewing in class is probably forbidden, it might be just enough activity to keep young PP patients from suffering attacks during class time. At any rate teachers should discuss with the child and parents the child's tolerance level for inactivity. Activity breaks must be built into the schedule so the child never sits longer than their tolerance level allows.