*Principles to Actions: Ensuring Mathematical Success for All*. Common factors, common multiples, strip diagrams, and double number lines are discussed in this, the third installment in the series.

^{*}Andrew Izsák, Andrew. Izsak@tufts.edu, is a professor of mathematics education at Tufts University in Medford, Massachusetts. He is interested in how students and teachers learn to reason with drawings to solve problems in the context of topics related to multiplication.

^{*}Sybilla Beckmann, sybilla@uga.edu, is a professor of mathematics at the University of Georgia in Athens. She is interested in how future teachers reason about multiplication, division, and proportional relationships and how to develop and deepen that reasoning.

^{*}Torrey Kulow, kulow@pdx.edu, is an assistant professor of mathematics education at Portland State University in Oregon. She is interested in future teachers' learning and development during their time in preparation programs as well as in supporting teachers in enacting standards-based mathematics instruction.