Two Digit Addition and Subtraction
Unit description: The students will use strategies and models to solve two digit addition and subtraction problems with and without regrouping within 100. They will also apply these strategies and models when solving one-step word problems with unknowns in all positions.
Download the complete Two Digit Addition and Subtraction framework to customize for your own planning.
Essential Outcomes of the Unit
Represent and solve problems involving addition and subtraction.
OA.1a. Use addition and subtraction within 100 to solve one-step word problems involving situations of adding to, taking from, putting together, taking apart, and comparing, with unknowns in all positions.
Use place value understanding and properties of operations to add and subtract.
NBT.5. Fluently add and subtract within 100 using strategies based on place value, properties of operations, and/or the relationship between addition and subtraction. Notes: Students should be taught to use strategies based on place value, properties of operations, and the relationship between addition and subtraction; however, when solving any problem, students can choose any strategy.
Other Standards Addressed in this Unit
Represent and solve problems involving addition and subtraction.
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.
Use place value understanding and properties of operations to add and subtract.
2.NBT.6. Add up to four two-digit numbers using strategies based on place value and properties of operations.
Essential Questions and Big Ideas
How can you use number sense to help when adding and subtracting 2-digit numbers?
- Number sense helps to solve addition and subtraction problems.
- Using multiple models to represent addition and subtraction helps to solve.
- Using mental strategies can allow for more fluent addition & subtraction
- Various methods and models can be used to represent and solve problems involving addition & subtraction
How can we apply our knowledge of addition and subtraction to solve word problems?
- 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.
Prerequisite Standards
NY-1.OA.1. Use addition and subtraction within 20 to solve one-step word problems involving situations of adding to, taking from, putting together, taking apart, and/or comparing, with unknowns in all positions.
NY-1.OA.2. Solve word problems that call for addition of three whole numbers whose sum is less than or equal to 20: e.g., by using objects, drawings, and equations with a symbol for the unknown number to represent the problem.
Assessment of these skills: Word problems allowing students to write and/or draw to find solutions, interactive math notebook entries, using a number line/ bar model/manipulatives to solve problems.
Download the complete Two Digit Addition and Subtraction framework to customize for your own planning.