This is good social and economic background material for youngsters, a sort of A.B.C. of how and what and why to buy. A few sidelights on what is behind advertising and radio programs, of how to sense real values, how to test, how to choose -- with examples drawn from things of real interest to boys and girls. Tie-up with plan for school cooperatives. A challenge to young buyers. The style is at times a bit written down, but on the whole it is a thoroughly useful job.