Should I be keeping my DC old books?

[Littlemissindifferent]

My DC is in YR8 and still has books from last year.

Should I be keeping any for revision or can I throw them away at the end of each year?

If they are like my DD1's old books they'll be useless for revision.

Thanks, I was hoping not to keep every book from every year!

My DC book are the same!