Antonyb has it about right. The senior cadet assumes a command appointment in the section and plans, briefs, rehearses and leads them through a section attack or similar. I remember when I did mine - nearly killed me (too many Mars bars).
Actually,I think it's getting the little darling's up in the morning on camp & away days!! (AND ,even worse,getting the little git's to go to sleep so we can have a pint in the mess!!<shandy of course.)