<P>The second edition of this book offers a unique approach to making mathematics education research on the teaching and learning of multiplication and division concepts readily accessible and understandable to preservice and in-service K-6 mathematics teachers.</P><P>Revealing students¿ thought processes with extensive annotated samples of student work and vignettes characteristic of classroom teachers¿ experience, this book provides teachers a research-based lens to interpret evidence of student thinking, inform instruction, and ultimately improve student learning. Based on research gathered in the Ongoing Assessment Project (OGAP) and updated throughout, this engaging and easy-to-use resource also features the following:</P><UL><LI>New chapters on the<I> OGAP Multiplicative Reasoning Framework and Learning Progressions</I> and <I>Using the OGAP Multiplicative Progression</I> to inform instruction and support student learning</LI><LI>In-chapter sections on how Common Core State Stand