Beginning with one of those pick-a-number games where you add, divide, etc., and end up with the number you picked, Weiss suggests ""keeping track of the number"" by putting that many jellybeans in a paper bag. (""No matter what you start with, you end up holding the bag."") From there, it's easy to understand that the bag functions as a SYMBOL for the unknown number, and then to let go of the bag and put a letter of the alphabet in its place. Now you're doing algebra--which is ""a bit like a mystery with numbers as clues""--and, before the abstractions have a chance to become intimidating, Weiss returns to jellybeans to introduce simple equations. An extracurricular mental munch, for those who prefer to go a step beyond amazing their friends with number games.