Welcome to the 2017 Teaching Children Mathematics (TCM) Focus Issue. According to Principles to Actions: Ensuring Mathematical Success for All (NCTM 2014, p. 23), for students to learn mathematics with understanding, they must have opportunities to engage on a regular basis with tasks that focus on reasoning and problem solving, have multiple entry points, and involve varied solution strategies. To solve such tasks, students must be able to understand and apply different tools and representations and move flexibly among them. Therefore, it is important for teachers to select and orchestrate discussions around highlevel tasks that provide opportunities for students to use different representations and apply their reasoning and problemsolving skills (5 Practices for Orchestrating Productive Mathematics Discussions, Margaret Schwan Smith and Mary Kay Stein. Reston, VA: NCTM, 2011).
This department is edited by Tonya Bartell, firstname.lastname@example.org, an associate professor of mathematics at Michigan State University.