I have kept all my son's primary, secondary school and college books and lots of notes. He wanted to throw them all out but I said he might one day have kids himself and they may come in handy. Provided you have room to store them, keep them for a couple of decades. You just never know if one day in the future someone close to you might find some use for them. ( Plus, they're nice to look over and reminisce about years later. It's amazing what memories looking through them can recall).