Students solve subtraction problems involving tens numbers by subtracting the tens digits without a model
A. Add tens numbers (Level 1)
B. Add tens numbers (Level 2)
C. Subtract tens numbers (Level 1)
E. Solve addition problems with 2-digit numbers and tens numbers (Level 1)
F. Solve addition problems with 2-digit numbers and tens numbers (Level 2)
G. Solve addition problems with two 2-digit numbers (Level 1)
H. Solve addition problems with two 2-digit numbers (Level 2)
I. Solve addition problems with two 2-digit numbers (Level 3)
J. Solve addition problems with two 2-digit numbers, including regrouping