- 1. Add Across a Ten or a Hundred
Add a small number or a multiple of ten by bridging to the next ten or hundred, using a pack-of-ten model, a number line, and a number sentence.
- 2. Take Away Across a Ten or a Hundred
Subtract a small number or a multiple of ten by hopping back to the ten or hundred below, using kiosk pictures, a number line, and a number sentence.
- 3. Carry the Ones
Add two 3-digit numbers in columns, wrapping ten ones into one ten and carrying it into the tens column.
- 4. Carry the Tens, Then Both
Add two 3-digit numbers in columns when the tens make a hundred, including sums with two carries and a 2-digit number lined up under a 3-digit one.
- 5. Exchange a Ten to Take Away
Subtract a 3-digit number in columns when there are not enough ones, by opening one ten into ten ones.
- 6. Exchange Twice, and Across a Zero
Subtract in columns when the tens need a hundred, when two exchanges are needed, and when a zero means opening a hundred before a ten.
- 7. Count Up to Find the Difference
Find the difference between two numbers by counting up through tens and hundreds, as when giving change, using number bonds to 100 and bar models.
- 8. Estimate, Then Check
Estimate sums and differences by rounding to the nearest hundred, and check answers with the inverse operation.
- 9. Make Decisions
Choose whether to add or take away, choose a mental or written method, and solve and check two-step problems with bar models.
