Researchers use an array of measures to provide lenses and levels of magnification for exploring teacher candidates' thinking. This paper describes five measures in terms of their costs, benefits, and the kinds of data each yields. These measures include a demographic questionnaire, concept mapping, a learning questionnaire, stimulated recall interview, and a short answer assessment. The measures are illustrated through a study involving 16 female teacher candidates. Among the most significant findings was the degree of correlation among the various measures and the differing information between the stimulated recall and the learning questionnaire. Qualitative analyses of the concept maps reveal more cognitive change than do quantitative analyses. The moderate correlation among the three primary knowledge measures (concept maps, learning questionnaire, and short answer assessment) means that candidates' structural, declarative knowledge is related to candidates' explicit self-reports, which are in turn related to tests of the content. An examination of these measures can be used to make important methodological decisions in future investigations of candidates' learning. (Contains 2 figures and 13 references.) (SLD)