This study examined the relation between teacher knowledge and teaching performance. In particular, it explored the association between preservice teachers' (PSTs) Mathematical Knowledge for Teaching (MKT) and their performance in five teaching practices considered conducive to establishing mathematically rich and intellectually challenging learning environments. Specifically, the study: (1) determined if there is an association between PSTs' MKT and their teaching performance, (2) explored the extent to which this association is mediated by factors such as PSTs' beliefs and background characteristics, and (3) uncovered ways that MKT manifests itself in PSTs' teaching performance. The association of interest was examined for 20 PSTs with respect to one time point (i.e., static perspective) - the beginning of their teacher education program - and with respect to changes between two time points (i.e., dynamic perspective) - before and after an intervention consisting of a two-term mathematics content/methods sequence.

A two-phase, mixed-methods approach was utilized to analyze the data collected through a multiple-choice test (to measure PSTs' MKT), an interview structured around a teaching simulation (to tap PSTs' teaching performance), and a survey (to gauge PSTs' beliefs and background characteristics). In the first phase, non parametric statistics were employed to explore the strength, direction, and robustness of the association of interest. In the second phase, seven PSTs' cases were scrutinized to develop more nuanced characterizations of the association.

The quantitative analysis showed a strong association between the PSTs' MKT and their performance in the teaching practices under investigation. From a static perspective this association was mediated by the PSTs' GRE-quantitative scores, but this factor did not mediate the gains in the PSTs' MKT and teaching performance. The qualitative analysis pointed to two factors - the PSTs' beliefs and their images of teaching - that appeared to inform the PSTs' teaching performance, apart from their knowledge. The cross-case analysis also suggested that the PSTs' knowledge can scaffold their activity in structuring the learning environments considered in the study by helping them maintain an emphasis on the meaning underlying the mathematical procedures at hand. The theoretical, methodological, and practical implications of the study findings are discussed.