A child at the small table is rarely just passing time. The figures that get left out, the story told again and again with tiny variations, the game that is abandoned at exactly the same moment each week - these are sentences, in a grammar we are still learning to read.
The work is not to interpret cleverly or quickly. It is to stay with what is being shown, to let it be shown fully, and to let the child feel that it has been received.
In time, the play tends to change on its own. That, more than any explanation, is usually the sign that something has moved.