The traditional K-3 social studies curriculum has focused on food, clothing, shelter, communication, transportation, and other cultural universals. Little information exists about children's prior knowledge and thinking (including misconceptions) about these topics. This study was designed to provide such information with respect to the topic of communication, and in the process to assess claims that primary-grade students do not need instruction in the topic because they learn what they need to know about it through everyday living. Individual interviews were conducted with 96 K-3 students, stratified according to grade level, achievement level, and gender. The students were asked about communication as a universal human need and the functions that it fulfills for us; methods of and limitations on communication in prehistoric times and among preliterate people who lived more recently; the impact of major inventions (writing, the printing press, radio, television, telephones, computers) on communication; communication by infants and among people who are blind or deaf; how people communicate when they do not share a language; how the environment and the culture shape vocabulary; the invention of new words; reasons for using symbols instead of words on certain traffic signs and other public notices; how the postal system works; why people read newspapers; and the workings of the television industry. The students' responses displayed many of the same patterns seen earlier in responses to interviews on shelter, clothing, and food: they knew more about the physical appearances of things than their underlying natures and more about the uses of products than about how they do what they do or what is involved in creating them. Sophistication of responses was related more closely to age (grade level) and personal experiences out of school than to achievement level or gender. Findings are discussed with emphasis on their implications for early elementary social studies. The study suggests that students stand to benefit considerably from more powerful treatments of cultural universals than those typically offered by textbooks. Contains a table and 51 references. The communication interview is appended. (Author/BB)