Add three and four digit numbers with and without regrouping, this time without the help of a place value chart. Use column addition to add, regrouping when necessary
A. Add two 4-digit numbers with and without regrouping in one place using a disk model
B. Add two 4-digit numbers with and without regrouping in two places using column addition and a disk model
C. Add two 4-digit numbers with and without regrouping in one place using a disk model part II
D. Add multi-digit numbers with regrouping in multiple places using column addition and disk models
F. Add multi-digit numbers using the standard algorithm