In this unit students will apply their understanding of the relationship between addition and subtraction to become fluent at solving addition and subtraction problems within 1000. They will also apply their understanding of the relationship between multiplication and division to become fluent in solving multiplication and division facts to 100. Before this, the students have only solved addition/subtraction and multiplication/division problems independently. In the final 4 lessons, students will use a letter to represent the unknown quantity in an equation.
Key Concepts:
 We can use the relationship between addition and subtraction to add and subtract within 1000. (Lesson 1)
 We can use the relationship between multiplication and division to multiply and divide within 100. (Lesson 4)
 We can represent unknown quantities in equations using letters. (Lesson 7)
Prior Knowledge Needed:
 Exploring equal groups as a foundation for multiplication and division; Grade 3, Unit 1; 3.OA.C.7
 Developing strategies for addition and subtraction; Grade 3, Unit 3; 3.NBT.A.2
 Understanding the relationship between multiplication and division; Grade 3, Unit 7; 3.OA.C.7
 Investigating patterns in number and operations; Grade 3, Unit 8; 3.OA.D.8
Units on the Horizon:
 4.OA.1 Introducing measurement conversions (Grade 4, Unit 6)
 4.OA.3 Using multiplication and division strategies with larger numbers. (Grade 4, Unit 2)
 4.OA.2 Solving problems using multiplicative comparison(Grade 4, Unit 7)
Lessons

Lesson objective: We can use the relationship between addition and subtraction to add and subtract within 1000. Students bring prior knowledge of developing strategies for solving addition and subtraction from 3.NBT.A.2. This prior knowledge is extended...

Lesson objective: Fluently add and subtract to 1000 using place value strategies. This lesson helps to build fluency with whole number addition and subtraction. An open number line is used here because it supports using the inverse operations to solve p...

Lesson objective: Relate the relationship between addition and subtraction to choose the most efficient strategy to solve a word problem. This lesson provides an opportunity for students to apply their knowledge and understanding of the relationship bet...

Lesson objective: Understand the relationship between multiplication and division to multiply and divide within 100. Students bring prior knowledge of the relationship between multiplication and division from 3.OA.C.7. This prior knowledge is extended t...

Lesson objective: Fluently solve multiplication and division problems to 100. This lesson helps to build fluency with whole number multiplication and division to 100. Equations with unknowns are used here because it supports using multiplication and div...

Lesson objective: Solve word problems using the relationship between multiplication and division. This lesson provides an opportunity for students to apply their knowledge and understanding of multiplication and division as inverse operations to a real...

Lesson objective: Understand that a variable represents an unknown quantity in an equation. Students bring prior knowledge of representing an unknown quantity with a symbol or picture in an equation from 1.OA.A.2. This prior knowledge is extended to usi...

Lesson objective: Solve twostep word problems including a variable. This lesson helps to build procedural skill with solving twostep word problems including a variable. A variable is used here because it supports the representation of the unknown quan...

Lesson objective: Solve twostep word problems including a variable in any part of the equation. This lesson helps to build procedural skill with solving twostep word problems including a variable in any part of the equation. A variable is used here be...

Lesson objective: Solve twostep word problems including more than one variable. This lesson provides an opportunity for students to apply their knowledge and understanding of using a variable to represent an unknown quantity to a reallife situation. S...