This is a perfect combo of my two favorite ideas for that space under the stairs leading to the basement. A reading nook AND book storage and shelves . assuming that there is enough space for this there.
DIY Lego table using Ikea Trofast storage system. On the top get a piece of wood or something for students to write on and then turn over to use Lego table. Then in the bottom put Legos in one, paper in other, crayons, etc.