**Chapter 5- Model Two-Digit Addition**

Summary

**5-1 Add Tens:** I can use mental math and basic facts to add tens.

**5-2 Count On Tens and Ones:** I can count on by tens and ones to add.

**5-3 PSS: Work Backward:** I can use the work backward strategy to solve problems

**5-4 Regroup Ones as Tens:** I can regroup 10 ones as 1 ten.

**Vocabular****y:** Regroup: to take apart a number to write it in a new way.

**5-5 Add One-Digit Numbers and Two-Digit Numbers:** I can add one-digit numbers to two-digit numbers with and without regrouping.

**5-6 Add Two-Digit Number:** I can add two-digit numbers with and without regrouping.

**5-7 Estimate Sums:** I can estimate the sum of two-digit addends by rounding.

**Vocabulary:** Round: to change the value of a number to one that is easier to work with.

**5-8 Add Three Two-Digit Numbers:** I can add three two digit numbers.

**5-9 PSS: Choose a Strategy:** I can choose the best strategy to solve problems.