This is the Teacher by Rhonda Go

This book is about a teacher all ready for school.
And also the students who rush through the door and drop sacks of lunches that smash! on the floor. Not to mention the snake that escaped, the cupcakes that flew, the bad bee that buzzed, the fountain that clogged, the kid who got sick and --Eek! There's that hamster that spins in a wheel! You'll be ready for a rest after enjoying this hilarious romp in which the lines--and chaos--build on each spread.

pages 32 10"x 10" paperback ages 4-8