The following webinar took place February 22, 2011 to address one of several resources from the Mathematics Improvement Toolkit from the National Forum to Accelerate Middle-Grades Reform. The webinar focused on the "Developing Student Understanding in Mathematics" online professional development module from the Toolkit. One of the developers of this resource, Steve Best, from Middle Start, walked participants through the free toolkit resources, pointing out how these materials can be used to help mathematics teachers understand and recognize strategies for selecting engaging tasks for students and analyzing student work to identify misconceptions. These materials address pedagogical considerations, strategies for planning, techniques for in-classroom instruction, and assessment strategies to help educators better support mathematics learning for middle-grades topics at a deep level. The focus of this, and other such modules, is to deepen student understanding of mathematics concepts, and help teachers recognize the particular planning and instruction considerations for middle-grades mathematics concepts.