The major purpose of this study was to investigate developmental patterns of understandings of four types of selected phenomena possessed by economically and racially different boys and girls. A total of 64 boys and girls, 32 blacks and 32 whites, were selected from Head Start, kindergarten, nursery, and primary schooling environments and then divided according to age and sex. Using a demonstration interview technique, the sample was examined regarding their understandings of the selected natural science phenomena. Each interview was videotaped. Attention was given to nonverbal and verbal responses. A rating of responses was applied by the investigator before treating and analyzing the data. A student's t-test and an analysis of variance were used (.05 level) to determine existing differences between and within groups. The study revealed that a significant ratio of variation existed between groups when classified according to sex, race, and age. Boys' understandings of such phenomena as electricity, seeds, human body, rockets, and evaporation were significantly greater than girls'. Older children had a significantly greater understanding than younger. The upper socioeconomic children had greater understanding than the lower. There was no significant difference between black children and white. Children's nonverbal response behavior was most evident in the area of rockets and space travel. (Author/EB)