This appealing ""Boston Children's Museum Activity Book"" shows boys and girls experimenting with balloons: devising propulsion models, measuring the force of air in balloons, and exploring the properties of air in confined spaces. Balloons and simple household items are used to make a balloon monorail, rocket boat, garbage-bag air mattress, air-bag platform, etc. Each project includes materials needed, step-by-step instructions with drawings, an analysis of ""What's Happening,"" and ""Further Challenges."" Safety notes are provided throughout. While some specialized terms (e.g., ""drag,"" ""friction,"" ""capacity"") are italicized and defined within the text, a glossary would have been helpful. Cheerful multiethnic drawings and an upbeat tone help make this an attractive science title for browers. No index.