This seems very removed from my own school days:
- find out what the children were doing at school: you couldn't, really, the curricula were not public. You could ask your kids after school, but I guess most parents were not really that interested anyway.
- what his children needed in their gym kit: shorts, t-shirt, sneakers. Every time. What else could it be?
- working out how to report them as sick: I suppose parents called the school in the morning(?) but as teachers were usually unaware of the reasons for a child's absence anyway they might as well not have done that at all. After the first term, the schoolmates would just inform all other teachers that X was sick, assuming so from the absence. Then, when X came back to school, they would bring a hand-written note from the parents explaining.