Resumen de Dylan's multidigit subtraction strategy

Rachael M. Welder, Megan Kelly Murray (ed. lit.), Jane P. Moore (ed. lit.)

• Without having been taught a method for solving subtraction problems that require regrouping, a first-grader applies his natural knowledge of numbers and operations to solve problems containing two- and three-digit numbers. This conversation features his reasoning as he formulates an explanation of the computational strategy he developed.

  Online extra: http://www.nctm.org/tcm010