In this culminating unit, students apply understandings gained throughout the entire year to demonstrate fluency in addition and subtraction. They practice solving various problem types, including adding to, taking from, putting together/taking apart, and comparison, with the unknown quantity in different positions. Students are given opportunities to select, justify and explain their strategies orally and pictorially as they make meaning of word problems. Students continue to build fluency to add and subtract within 20 by using known addition and subtraction facts to solve complex problems.
Key Concepts:
 The meaning of addition and subtraction do not change no matter which tools we are using.
 We can solve many kinds of problems using addition and subtraction.
 We can use addition and subtraction facts we already know to help us solve addition and subtraction problems we haven't seen before.
Prior Knowledge Needed:
 Understand addition as “putting together and adding to” and subtraction as “taking apart and taking from”; (Grade K, Unit 6; K.OA)
 Represent and solve addition and subtraction problems of all types; (Grade 1, Unit 9; 1.OA.A.1)
 Add and subtract within 20 using strategies such as counting on; making ten; decomposing a number leading to a ten, and using the relationship between addition and subtraction; (Grade 1, Unit 9; 1.OA.A.C.6)
 Work with addition and subtraction equations; (Grade 1, Unit 9; 1.OA.D.7)
 Associative and Commutative Properties; (Grade 1, Unit 15; 1.OA.B.3)
Units on the Horizon:
 Grade 2, Unit 1; Adding and subtracting within 100
 Grade 2, Unit 8; Relating skip counting to mental addition and subtraction
Lessons

Lesson objective: Understand that the meaning of addition and subtraction do not change, no matter which tool we are using. Students bring prior knowledge of the meaning of addition and subtraction as "add to/take from" and "put together/take apart" fro...

Lesson objective: Solve word problems using a number line and check answers using another tool. This lesson helps to build fluency with solving addition and subtraction word problems and using multiple tools to solve and check computation. Tape diagrams...

Lesson objective: Apply understanding of addition and subtraction and knowledge of using a variety of tools to solve problems and to create equations. This lesson provides an opportunity for students to apply their understanding of the meaning of additi...

Lesson objective: Understand that we can use both addition and subtraction to solve many kinds of problems. Students bring prior knowledge of using objects and drawing to solve a variety of situational problems involving addition and subtraction from Gr...

Lesson objective: Solve addition and subtraction word problems using tape diagrams and equations. This lesson helps to build fluency with solving "Put Together/Take Apart" and "Add To/ Take From" word problems. Tape diagrams are used here to make a pict...

Lesson objective: Solve comparative word problems using a tape diagram and equation. This lesson helps to build fluency with solving comparative word problems. Tape diagrams are used here because it supports students' ability to interpret word problems ...

Lesson objective: Apply understanding of addition and subtraction situations to create story problems to describe a picture. This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction situatio...

Lesson objective: Understand that we can use addition and subtraction facts we already know to solve new addition and subtraction facts. Students bring prior knowledge of decomposing 10 from Grade K, Unit 12 K.OA.4. This prior knowledge is extended to d...

Lesson objective: Find equivalent but easier problems for math facts using "doubles +1" and "doubles 1" strategies. This lesson helps to build fluency in adding and subtracting numbers to 20 by having students create equivalent but easier sums using "d...

Lesson objective: Apply understanding of composing and decomposing numbers to match equivalent values. This lesson provides an opportunity for students to apply their knowledge and understanding of creating equivalent but easier problems to a reallife ...