With adult help, even preschoolers can explore science! The author of Bird Count! (2019), illustrated by Stephanie Fizer Coleman, contributes the fourth title in the Busy Little Hands series of hands-on learning activities. These 20 projects serve as age-appropriate introductions to physics, earth science, chemistry, and biology. The directions are relatively simple, with few steps and clear results. A mix of photographs and illustrations showing diverse preschoolers allow the nonreading child to follow along step by step. Each project begins with "grown-up prep steps": necessary materials, where to do the activity, and sometimes extension suggestions. The materials are easily available. Some projects, such as "Cereal Static" (demonstrating static electricity) or "Pulley-Up" (using a simple machine to lift a load) can be done in a short period; others, such as growing seeds or exchanging weather information with someone who lives in another climate, might be long-term. A beginning bird-watching activity could introduce long-running citizen science projects. The last few pages, for older helpers, detail the concepts explored through each activity. What's most intriguing about this collection is the direct connection to the scientific method, explained to children at the beginning as asking questions, guessing answers, trying something out, seeing what happens, and pondering the results. With this introduction and some help with record-keeping (charts and graphs are among the illustrations), youngsters will develop good science habits while they are learning. A well-thought-out addition to the science activities shelf. (suggestions of items for a science field kit) (Science activity book. 3-7) Copyright (c) Kirkus Reviews, used with permission.