Summary.This paper describes the responses of more than 1,200 children to a schedule of seventy questions dealing with estimation of length, time, direction; with volume, weight, shadows, etc. Several questions were concerned with growth of living things. The replies to two questions concerning sky and night are classified according to nature of response. Results are tabulated in terms of percentages for boys and girls with increasing chronological age, and the types of questions considered in terms of the age trends.