One day, the teacher says that, from now on, two plus two is five. Nearly everyone accepts the new maths. And other strange things happen too. Suddenly there’s a zebra in the class; she says her name is Ariane. Ozzie goes to buy a joke to impress Ziva, but can’t find one that he can afford. Noepy takes part in a demonstration against the abolition of crying. Ziva’s family take it in turns to have hiccups.