With this construction, I also created some unique spaces in which the children could operate. There was the space underneath the horizontal box over the yellow table. There was the space inside the horizontal box.
There was also the space inside the box next to the table. That space was different because it was surrounded by high cardboard walls and accessed through deep openings cut in the sides of the box. That space was also intriguing because the horizontal box encroached into the volume of that box and the encroachment created new spaces underneath and on both sides.