Solve one-step addition and subtraction equations by using a symbol to represent an unknown number ...

by explaining what the symbol in a given addition or subtraction equation stands for.

In the equation
3 + ▲ = 10, the triangle stands
for the number (7) that would
make the equation true.

by creating an addition or subtraction equation with a symbol to represent the unknown operation.

In the equation
3 ▲ 7 = 10, the triangle stands for
the number (7) that would make
the equation true.

by giving a different symbol for the unknown in a given addition or subtraction equation.

by solving, using manipulatives, a given addition or subtraction equation with a symbol to represent the unknown operation.

by solving a given addition or subtraction equation with one unknown, using strategies, such as guess and test.

by solving a given addition or subtraction equation when the unknown is on the left or the right side of the equation.

by explaining why the unknown in a given addition or subtraction equation can only have one possible value.