sarah tells a joke:

"mummy, there's this girl in my school, she thinks magnum opus is an ice-cream! hahahahahaha!"
adults in her family, variously: "oh, it isn't?"
sarah looks at her family in disbelief.

sarah and ariel and ariel's school friend are in the car.

ariel's friend to ariel, in the back seat: "what do you use to cut the sea in half?" (answer: see saw)
sarah turning around in the front seat: use a trident?
boys: see saw! see saw! heeheeheeheehee!
sarah: not a trident? why not a trident?
boys, giggling: see saw! see saw!
sarah looks at the boys with great contempt.

(what a good thing she is going to rosyth next year.)