Use place value understanding and properties of operations to add and subtract. 1.NBT.4 Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.

1.NBT.5 Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used. Tasks 1.NBT Task 4a 1.NBT Task 4b; 1.NBT 4b BLM

1.NBT.6 Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Tasks 1.NBT Task 5a; 1.NBT 5a Student Form 1.NBT Task 5b; 1.NBT 5b Student Form 1.NBT Task 5c; 1.NBT 5c BLM

## Number and Operations in Base Ten Tasks

Use place value understanding and properties of operations to add and subtract.1.NBT.4Add within 100, including adding a two-digit number and a one-digit number, and adding a two-digit number and a multiple of 10, using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used. Understand that in adding two-digit numbers, one adds tens and tens, ones and ones; and sometimes it is necessary to compose a ten.Overview of Problem Types (Glossary, Table 1).

Tasks1.NBT Task 3a; 1.NBT 3a Student Form

1.NBT Task 3b; 1.NBT 3b Student Form

1.NBT Task 3c; 1.NBT 3c Student Form

1.NBT Task 3d; 1.NBT 3d Student Form

1.NBT Task 3e; 1.NBT 3e Student Form

1.NBT Task 3f; 1.NBT 3f Student Form

1.NBT.5Given a two-digit number, mentally find 10 more or 10 less than the number, without having to count; explain the reasoning used.Tasks1.NBT Task 4a

1.NBT Task 4b; 1.NBT 4b BLM

1.NBT.6Subtract multiples of 10 in the range 10-90 from multiples of 10 in the range 10-90 (positive or zero differences), using concrete models or drawings and strategies based on place value, properties of operations, and/or the relationship between addition and subtraction; relate the strategy to a written method and explain the reasoning used.Tasks1.NBT Task 5a; 1.NBT 5a Student Form

1.NBT Task 5b; 1.NBT 5b Student Form

1.NBT Task 5c; 1.NBT 5c BLM