One area explored in the second (in-depth) phase of the Learning in Science Project was "children's science," defined as views of the world and the meanings for words that children have and bring with them to science lessons. The investigation reported focuses on the concept of "plant" held by 29 students. Data were obtained by the "interview-about-instances" procedure in which students were shown cards with diagrams which represented different instances (grass) and non-instances (elephant) of the concept. Students were asked "In your meaning of the word 'plant,' is ...(the drawing shown)... a plant?" At the end of the interview, students were then asked to give their meanings of the word in a sentence or two. Responses are presented, discussed, and analyzed according to: (1) the use of scientifically acceptable critical attributes (leaves, flowers, and others); (2) the use of scientifically unacceptable critical attributes (size, hardness, and others); (3) the use of critical attributes of living things as the critical attributes of plants; and (4) the atypical plants (seaweeds, seeds, and others). Among results are findings that only four students could categorize instances.non instances correctly. Sample interview cards and additional quotations, under the same four headings enumerated above, are provided in an appendix. (JN)