\input zb-basic \input zb-matheduc \iteman{ZMATH 2016f.00596} \itemau{Boote, Stacy K.} \itemti{Choosing the right tool.} \itemso{Teach. Child. Math. 22, No. 8, 476-486 (2016).} \itemab Summary: Students' success with fourth-grade content standards builds on mathematical knowledge learned in third grade and creates a conceptual foundation for division standards in subsequent grades that focus on the division algorithm. The division standards in fourth and fifth grade are similar; but in fourth grade, division problem divisors are only one digit; whereas in fifth grade, divisors are two digits. The division model explained in this article uses groupable base-ten manipulatives to teach the fourth-grade division standard. By carefully selecting the right tool for the instructional task, teachers can keep their students' focus on place value, allow for easy manipulation of the materials, and emphasize division's base-ten structure -- all to build conceptual understanding. Three recent articles in TCM'' [{\it L. L. Cooper} and {\it M. C. Tomayko}, ibid. 17, No. 9, 558--567 (2011; ME 2011e.00535); {\it P. A. Sellers, ibid. 16, No. 9, 516--520 (2010; ME 2010e.00381); and {\it J. F. Martin jun.}, ibid. 15, No. 8, 482--487 (2009; ME 2009e.00114)] offered support for teaching division and place-value concepts. This article expands on these and explains how using groupable'' instead of pregrouped'' base-ten materials will better support students' conceptual and procedural understanding of division. (ERIC) \itemrv{~} \itemcc{D40 U60 F30} \itemut{teaching methods; mathematical concepts; concept formation; manipulative materials; division} \itemli{http://www.nctm.org/Publications/Teaching-Children-Mathematics/2016/Vol22/Issue8/Choosing-the-Right-Tool/} \end