One highly effective thing you can do to help your children with their homework and study in general is to get a whiteboard at home.
Over the years I’ve found that writing / drawing / explaining on an A4 pad has its limitations.
I fixed an A1 whiteboard to my a wall in my children’s bedroom and their answer any question (where possible) on the whiteboard. Once it’s up there, the children can reference it while they continue their homework.
It’s actually become a game, in that I can write a question on the whiteboard and usually in the following 24 hours it’s been answered.
It’s become a favourite at bedtime for me to pick a subject at random (last night it was “What is radioactivity?”). When my girls woke up this morning they were still thinking and talking about protons, neutrons, electrons, heavy metals and Marie Curie.
Including pens and the eraser it’s probably the most effective £45 I’ve spent on furthering my children’s education.