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.F

Description:

generate and solve problem situations when given a number sentence involving addition
or subtraction of numbers within 20.

Standard:

1.5.F

Description:

determine the unknown whole number in an addition or subtraction equation when the
unknown may be any one of the three or four terms in the equation; and