This presentation aims to discuss one of the assumptions that individual knowledge assessment relies on, namely that of meaning- or message-transfer (as in Linell, 2009). I adopt a dialogical theoretical perspective (ibid) by which I explore the interaction between students and test-questions in a test of scientific literacy (through which the students’ knowledge is to be evaluated). The question is how the positivistic assumption of message-transfer translates in the students’ meaning making of the test items and how the texts, illustrations and everyday context in the test are being negotiated among students? In its methodology this study departs from the presumption that meaning making should be studied in action. Therefore, situations were constructed in which 15 year old students worked with a selection of PISA science problems collaboratively in small groups (n=21). In total, 16 hours of videotaped talk and actions were produced and have been transcribed and content- and semantically analyzed. Test-occurring words, such as “reference”, “factor” or “pattern” (which can be seen to have an intended meaning in the test) appear to be interpreted within other contexts and with other meanings. It is argued that meanings are not unambiguously transferred. Further, ambiguity is reinforced by the descriptions of everyday context and mathematical illustrations, like graphs and diagrams, in the test. The results are valuable for interpreting the claims and results of knowledge measurements. Reference: Linell, Per (2009): Rethinking language, mind, and world dialogically: interactional and contextual theories of human sense-making. Information Age Inc.