Devised by a staff member at Boston Children's Museum, the activities put forth here are neither idle time-passers nor grim demonstrations of scientific principles, but rather suggestions for playing around with the materials or devices in a way that naturally leads to questions about their properties. . . and the questions lead in turn to more activities. The most structured of the three books uses ballpoint pens as instruments--balances, hydrometers, eyedroppers--to investigate liquid weight, capillary action, and other phenomena which, as presented here, add up to an explanation of the workings of the ball-point pen itself. The emphasis is on fun in the bubble book, with only a hint--for those who would go further--of the mathematical relationships and ""shaping forces of nature"" which bubbles can demonstrate; but meanwhile there are tips for making bubbles and soap-film curves of different sizes, shapes, groupings, and duration, as well as a challenge to try new bubble structures and to think about how they are formed. The milk cartons are filled with sand and cut and combined to make variously shaped blocks for building towers, furniture, or whatever. Beams for houses lead naturally on to bridges, then to arches. There are no detailed step-by-step directions; rather Zubrowski encourages finding out which arrangement will make the strongest wall, the optimum arch, and so on. Though home use is suggested, the photos show a classroom setting, and the absence of answers to Zubrowski's prodding questions makes this better suited to groups--perhaps with a discreet, non-intervening adult presence. Together or separately, an excellent resource for class, club, or playground.