Three-Digit Addition and Subtraction
Unit description: In this unit the students will learn to represent and solve three digit addition and subtraction problems within 1,000. Students will recognize when it is necessary to compose or decompose tens or hundreds. They will apply their understanding of the relationship between addition and subtraction to solve two-step word problems.
Download the complete Three Digit Addition and Subtraction framework to customize for your own planning.
Essential Outcomes of the Unit
Number and Operations in Base Ten- Use place value understanding and properties of operations to add and subtract.
- NY-2.NBT.7a . Add and subtract within 1000, 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 representation. Note: A written representation is any way of showing a strategy using words, pictures, or numbers.
Other Standards Addressed in the Unit
Number and Operations in Base Ten- Use place value understanding and properties of operations to add and subtract.
- NY-2.NBT.7b Understand that in adding or subtracting up to three-digit numbers, one adds or subtracts hundreds and hundreds, tens and tens, ones and ones, and sometimes it is necessary to compose or decompose tens or hundreds.
Operations and Algebraic Thinking- Represent and solve problems involving addition and subtraction
- NY-2.OA.1b Use addition and subtraction within 100 to develop an understanding of solving two-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions.
Essential Questions and Big Ideas
How do we solve three digit addition problems?
- Strategies such as modeling, using 10s blocks, extended form, mental math and standard algorithms can be used to solve addition within 1,000.
- Some multi-digit addition problems involve regrouping 10s to the next place value.
How do we solve three digit subtraction problems?
Strategies such as modeling, using 10s blocks, extended form, mental math and standard algorithms can be used to solve subtraction within 1,000.
Some multi-digit subtraction problems involve regrouping 10s to the prior place value.
How do we check our answers when adding and subtracting within 1,000?
- The reverse relationship between addition and subtraction can be used to check answers.
How do we solve two step word problems involving addition and subtraction within 100?
- Identifying key words and understandings within word problems can help determine whether to add or subtract to solve problems in our daily life.
- Understanding of properties of operations and the relationship between addition and subtraction can help to solve word problems.
- Marking up the question and drawing pictures can help to visualize word problems.
Download the complete Three Digit Addition and Subtraction framework to customize for your own planning.