use objects and pictorial models to solve word problems involving joining, separating,
and comparing sets within 20 and unknowns as any one of the terms in the problem such
as 2 + 4 = [ ]; 3 + [ ] = 7; and 5 = [ ] - 3;
Standard:
1.3.E
Description:
explain strategies used to solve addition and subtraction problems up to 20 using spoken
words, objects, pictorial models, and number sentences; and
Standard:
1.5.D
Description:
represent word problems involving addition and subtraction of whole numbers up to 20
using concrete and pictorial models and number sentences;