story of the family pet (hamster? guinea pig?) that eats the terribly tasting discarded cereal that turns out to contain 100% additives and so grows very large. The publication date is pre-1964 — the year the book was read to my 6th grade class by Mrs. Wanless.
Stump the Bookseller
New format, same book stumper solving.
Perhaps “Mr. Twigg’s Mistake” by Robert Lawson?
Thanks so much. I’m sure that “Mr. Twigg’s Mistake” is it. You’ve helped me in my little project of re-creating my last year (of 7!) in Rosemary Elementary School in Chevy-Chase, Maryland.