Organising the threads was a project we did one morning. A girl mentioned that her mom has a little box with pieces of plastic that each thread is wound on. So we got a big piece of thick card and cut strips of it as long as the drawer and about 3 cm wide. We cut small triangles out on each end as above.
All the children wanted to join in the winding, it was a very social activity. Once all the threads were wound on their card pieces we put them back in the drawers and they looked as neat as could be.