This book contains hands-on science laboratory activities for grades 4 through 9 that use discrepant events to challenge students. All of the "puzzlers" are based upon science principles and include directions for building gadgets that explain the "puzzlers." Topics covered include: volume conservation, magnetic phenomena, optical illusions, acceleration and velocity, center of gravity, Bernoulli's principle, tree growth, perpetual motion, heat transfer, projectiles, melting, and carbon dioxide. (MKR)