Simple explanations of complicated concepts (nocturnal and diurnal creatures, the rotation of the earth, etc.) are presented with colorful cartoons. But unlike the Gordons' recent Fun with Color (p. 945), this book, for the same age group, is not as successful. The language is imprecise and often ambiguous, and the suggested activities are impractical. Children are encouraged to ask adults to make a chart of the sun's course during the day. ``Do this on summer and winter days. The sun seems lower in winter.'' No guidance is given on how the chart is to be made or data recorded; it's unlikely that children will follow through with a six-month comparison. Elsewhere, the author states, ``Sunlight lets you know that it is day. Blind people's eyes do not work. They use special clocks to tell them when it is day or night.'' Such sentences will be a little bald for some readers and just plain misleading for others. (further reading, index) (Nonfiction. 5-7)