This study explored a group of elementary teachers' ("n" = 35) learning to construct high-quality lesson plans that foster student understanding of fundamental mathematical ideas. The conceptual framework for this study was gleaned from the recently released Institute of Education Sciences (IES) recommendations, including (a) interweaving worked examples and practice problems, (b) connecting concrete and abstract representations, and (c) asking deep questions to elicit student self-explanations. Comparisons between teachers' pre- and postsurveys, and among teachers' initial, revised, and end-of-course lesson plans, indicated teachers' growth in using worked examples, representations, and deep questions during their lesson planning. Issues related to teachers' learning as they constructed lesson plans that aligned with the IES recommendations were also revealed. (Contains 3 tables and 5 figures.)