This study has two purposes: (a) methodological--to design and test a new instrument able to reflect changes in attitudes toward science over time, and (b) investigative--to find out the effect of two similar curricular treatments on the attitudes of two classes. Items about the relevance of science to students' lives were developed, pilot-tested, and analyzed using Rasch modeling. We then divided reliable items into three equivalent questionnaire forms. The final three forms of the questionnaire were used to assess high school students' attitudes. Over 18 weeks, one class used a core curriculum (Science and Sustainability) to learn science in the context of making decisions about societal issues. A second class used the same core curriculum, but with parts replaced by computer-based activities (Convince Me) designed to enhance the coherence of students' arguments. Using traditional and Rasch modeling techniques, we assessed the degrees to which such instructional activities promoted students' beliefs that science is relevant to them. Both classes tended to agree more, over time, that science is relevant to their lives, and the increases were statistically equivalent between classes. This study suggests that, by using innovative, issue-based activities, it is possible to enhance students' attitudes about the relevance of science. (Contains 1 table and 2 figures.) Appended are: (1) CARS Items; (2) Science Attitude Item Fit Statistics; and (3) Interpretation of Science Attitude Logit Scale. (Contains 1 table, 2 figures, and 2 notes.)