That's Not A Hippopotamus! by Juliette MacIver and Sarah Davis

A school trip to the zoo descends into a chaotic hunt for the missing hippopotamus. Teacher, zookeeper and all the children join the search. The noise and drama reach a pitch, and no one thinks to listen to quiet Liam, who really might know where the hippo is hiding.

I see him, Miss! He’s super tall!
I’ll fetch him in no time at all.
I got’im, Miss! I got’im, Miss!
I KNEW that I could spot’im, Miss!