Polly the parrot came to visit PlusKids to show us that maths can be genuinely fun.
A character walking into the classroom completely changes the children's relationship with an exercise. When it is Polly asking for an answer, it is no longer a task set by an adult but a game you join willingly — and children who usually hesitate to put their hand up will try, because it no longer feels like being tested.
It is a simple trick, as old as the hills, and it works precisely because it shifts attention from "somebody is checking on me" to "I want to see if I get it right". The sums get done just as well; it is only that nobody is counting them any more.