Butterflies in my Stomach and Other School Hazards by Serge Bloch

From chapters.ca:
You can bet your bottom dollar this funny story is the cream of the crop — and the best thing since sliced bread! Award- winning artist Serge Bloch will have kids laughing their heads off at this child’s- eye look at idiomatic expressions like "ants in your pants," "homework is for the birds," and "cat got your tongue?" These commonly used sayings make sense in the adult world, but just imagine what a child pictures when she hears it’s "raining cats and dogs!" With witty and wonderful images that mix whimsical line drawings with photographs of inanimate objects, Bloch gives us a unique and sympathetic perspective on a boy’s first day of school where colorful butterflies flutter in our hero’s stomach and a cloud rains on him when he’s "under the weather." Even the "big cheese" Principal has a body cut out of a block of Swiss.