In this unit, students will begin to reason and solve addition and subtraction problems. They will build on strategies and problem types they are familiar with from Kindergarten, extending the number range to 20. The use of data will provide a context for students to make important connections to addition and subtraction and the relationship between the two operations. Students may struggle to understand how counting on not only relates to addition, but also can be used in solving subtraction problems.
Key Concepts:
 We can organize, represent, and interpret data to answer questions about situations.
 We can use counting to add because counting on more is the same as adding on more.
 We can use counting to subtract because figuring out how many to count on is the same as figuring out how many were added on.
Prior Knowledge Needed:
 Classify objects into categories, count the number of objects in each category (Grade K, Unit 3); K.MD.B.3, K.CC.B.5.
 Add and subtract to 5 (Grade K, Unit 4, Grade K, Unit 6); K.OA.A.1, K.CC.B.5.
 Add and subtract to 10 (Grade K, Unit 10; K.OA.A.4).
 Composing ten (Grade K, Unit 12; K.OA.A.4).
Units on the Horizon:
 Extending strategies for solving addition and subtraction problems (Grade 1, Unit 9).
 Generating and representing measurement data to solve problems (Grade 2, Unit 9).
 Relating addition and subtraction to length (Grade 2, Unit 3).
Lessons

Lesson objective: Organize and represent data into categories. Students bring prior knowledge of classifying objects from K.MD.B.3. This prior knowledge is extended to organizing and representing data as students are given a set of objects that can be o...

Lesson objective: Collect, organize, and represent data based on like traits. This lesson helps to build procedural skills with organizing and representing data. Modeling with twosided counters is used here because it supports students as they collect ...

Lesson objective: Answer questions about a set of data by interpreting a visual representation. This lesson helps to build procedural skills with interpreting data. A picture graph with organized data is used here because it supports students in focusin...

Lesson objective: Organize, represent, and interpret a data set into categories. This lesson provides an opportunity for students to apply their knowledge and understanding of data to a reallife situation. Students are asked to organize a batch of thre...

Lesson objective: Organize additional data into a data set by using counting on to add. Students bring prior knowledge of counting by ones and adding from K.CC.B.5 and K.OA.A.2. This prior knowledge is extended to relating counting to addition as studen...

Lesson objective: Count on to add two numbers together. This lesson helps to build the procedural skill of counting on to add. Pictures and number sentences are used here because they support students' understanding of counting on through visuals and re...

Lesson objective: Apply the counting on strategy to add data into an organized data set. This lesson provides an opportunity for students to apply their knowledge and understanding of counting on to a reallife situation. Students are asked to organize ...

Lesson objective: Understand how to use counting on to subtract data from an organized data set. Students bring prior knowledge of subtraction and counting by ones from K.CC.B.5 and K.OA.A.2. This prior knowledge is extended to using counting on as a st...

Lesson objective: Relate counting on to subtraction to solve subtraction situations. This lesson helps to build procedural skill with counting to subtract. Modeling with number sentences is used here because it supports relating addition and subtraction...

Lesson objective: Use counting on to solve subtraction situations in the context of data. This lesson provides an opportunity for students to apply their knowledge and understanding of operating with data to a reallife situation. Students are asked to ...