Sideways Arithmetic from Wayside School by Louis Sachar, 1989.

This is a companion book to the Wayside School Series.  Unlike the other books in the series, it doesn’t contain stories.  It talks about the things that kids at Wayside School study, partly from the point of view of Sue, a new student who is stunned to learn that kids at Wayside School do arithmetic with words, not numbers.

Basically, it’s a puzzle book.  In the Arithmetic section, the letters in the words stand for numbers.  The book gives an example to demonstrate how to figure out which numbers the letters stand for.  The problems get harder through the sections labeled Numbers, Pronouns, and Paragraphs.

From the Recess section on, there are logic puzzles.  In Recess, you have to use the information provided to figure out what games the children play at recess.  In Science, Geography, Etc. (that’s one chapter), you have to figure out who got the right answers to the tests from the information provided. You see the answers five of them got and know that only one of them got all the answers right and no two of them had the same score. When you look in the back to see if you solved the problem right, you get to see what the test was actually about, and that’s the funniest part.  The Lunch section combines logic puzzles with math.  The True or False section gives you true/false questions to answer based on a series of statements about which of them are true or false.  Finally, in the After School section, Joy and Sue give up and go home (as well they should).

I like the book because I like puzzles, and there are funny little stories around the problems and answers.  All of the puzzles are answerable (except for one or two where the correct answer is that they’re impossible, which is why Joy should definitely get up and go home, but you’ll figure that out way before she does).  If you like puzzles and the Wayside School series, you’d like this book.  If you don’t like puzzles, you can skip this and just stick to the regular books in the series (as regular as Wayside School gets).  If you like puzzles but don’t know about the Wayside School series, you could still find it interesting but you wouldn’t really appreciate the funny parts.  If you don’t like the Wayside School series or puzzles, you probably aren’t reading this right now, so don’t worry about it.