Students use the prior strategies to solve 2-digit subtraction equations
A. Use base-10 blocks to add a 2-digit number to a tens number
B. Add a 2-digit number to a tens number, without a model
C. Use base-10 blocks to add 2-digit numbers
D. Use understanding of place value to solve addition equations
E. Solve addition equations with 2-digit numbers
F. Solve more addition equations with 2-digit numbers
G. Use base-10 blocks to solve addition equations requiring exchanges
H. Use place value cards to solve addition equations requiring exchanges
I. Solve 2-digit addition problems without a model
J. Use base-10 models to solve subtraction equations
K. Solve 2-digit subtraction equations
L. Decompose 2-digit numbers
M. Decompose numbers as a strategy to solve 2-digit subtraction equations
N. Solve more 2-digit subtraction equations by decomposing numbers
O. Use making tens as a strategy to solve 2-digit subtraction equations