the shotas got naked or half naked in the beginning like they did last time when she was showing them the anatomy of their penises to them practically, i think the boys are going to say they had trouble masturbating because... their imagination wasn't working well, this might trigger the lingerie show for the boys where she'll guide them with what to do and this lead to (as someone else had suggested); one climaxing quickly, other by using a handjob and lastly the climax of the update she giving the last boy who's tougher than the other brothers getting an educational blowjob to teach them that there's more ways of ejaculating and this will demonstrate the trifecta of the first 3 ways a boy will learn how to ejaculate, one from his own hand, second from handjob and third by blowjob.
if it is speculated and turned right that she bought something that was plastic looking, it could be cleaning products because she already knew what she hand planned and what type of mess it'll create during this lesson. otherwise, someone else suggested its going to be a mess to get off the floor, possibly furniture, their own clothes and herself.