Hans is in the treehouse. There is a code to access it.
It is written down somewhere. Did you find any clues?
Somewhere in the class room, maybe? ?
Look, again, into your desk.
It was "left, right, right, middle, left, right, left".
Next to the treehouse there are three stones. Click on them in order.
"left, right, right, middle, left, right, left"