See, look at Mo's enthusiasm for Yeti's. It was contagious or hilarious. Depends on how you look at things. Nigel opened his borrowed copied to a random page. Well it was just facts that he already knew about the things from Mo. Like they were 15 feet tall and the other muggle names for them.

And look who makes a fabulously random entrance. Headmistress. That red hair can only mean it was her and she was look for that kid who made the awesome entrance at the beginning of class.

He would rather watch this random event. Than spout facts about a Yeti.