I know it is not really a dome; a dome is rounded on top. It is a box with holes, but that does not do it justice. It does not do it justice because the play it elicits from the children is exquisite, like the shape of a dome. That is enough poetic license for now. Sorry.
The truth is that the box over the horizontal channels changed the nature of play because it added intriguing spaces for exploration. For children the equation works something like this: more intriguing spaces equals more exploration.
Let's look at some spaces the children discovered to explore and what those explorations looked like.
First, there are the openings created by the box over the channels. In the picture below, the boy keeps running the palm of his hand under the edge of the box over and over again. Why? To see what it feels like, of course.
From feeling the edge of the box, this child starts to feel the corn by reaching under the the partition. His hand is totally immersed in the corn. Immersing his hand under the partition has to be a different sensation that simply immersing his hand in an open channel. The feeling of immersing in this instance is totally cut off from his vision by the partition. As you can see, this two-year-old finds this part of the box appealing and worthy of exploration.