Class 6 ICSE science is now three separate books, and I'm travelling two nights a week

My elder son moved up to class 6 and science has split into physics, chemistry and biology, each with its own book and teacher. Three weeks in, the chemistry chapter has him memorising symbols with no idea why, and the physics teacher wants definitions word for word. I'm away for customer demos most weeks and my partner's days are long, so homework help is patchy, and our class 1 boy needs someone sitting with him too. For parents whose children went through this split: did it settle by itself after the first term, or did you have to step in? I'd rather not add tuition at 11 if this is just the adjustment period.