Are there 3 bookcases? Would they be able to fit on the end wall? I'm not sure I'd want desks facing a wall. You could then have a long table under the fan that could serve as a desk. I would then move the piano to the wall where the bookcases had been. Perhaps a small couch facing the fireplace. You might want a blackboard/whiteboard on wheels for teaching purposes.

Might be an idea to have any writing surfaces near the natural light of the sliding door. Which then gels with the seating collection near the fire place. Seating could be bean bags or chairs, large poufs?

I would get rid of all the current furniture and start new. The whole room can be furnished from Ikea for a reasonable price. First, I would paint the brown wainscot white and the walls a soft grey. I would cover up the ugly brick on the fireplace with fresh white shiplap or a white or grey tile. Add a grey sectional that faces the fireplace with a TV above for education videos and a white board on the wall beside it for lessons. Behind the couch will be storage and a table for school activities. On the empty wall where the book cases are currently go to ikea and get modular desks with butcherblock counter tops for a workstation. The color pallete of the room is going to be cools greys accented with pops of color to create a welcoming learning enviorment. I attatched photos of a rendering of your room down below