In this unit, students continue their work with addition and subtraction. Students have previously learned how to apply understandings of the properties of operations to add and subtract within 10. Students extend their knowledge through the use of new strategies such as decomposing and making tens. Students will also use objects and drawings to represent addition and subtraction situations. Students will be introduced to the equals sign as a symbol that represents the same amount on both sides of an equation. They will be using comparison language, such as “how many more” and “how many less” to analyze and interpret bar graphs using known quantities.
Key Concepts:
 Objects and drawings can be used to represent and solve different problem types (add to, take from, put together, take apart, and comparing with unknowns in all positions) involving addition and subtraction.
 We can use strategies such as making ten, counting on, decomposing a number leading to a ten, and the relationship between addition and subtraction to add and subtract within 20.
 The equal sign indicates equivalence and means that the expressions on either side of the equals sign have the same value.
 We can organize, represent and interpret data (up to three categories) and make comparative statements about the values in the categories using our knowledge of quantities.
Prior Knowledge Needed:
 Apply properties of operations as strategies to add and subtract; (Grade 1, Unit 6; 1.OA.3)
 Understand subtraction as an unknownaddend problem; (Grade 1, Unit 6; 1.OA.4)
 Compare two twodigit numbers; (Grade 1, Unit 8; 1.NBT.B.3)
 Organize, represent, and interpret data up to 3 categories and ask and answer “total” questions; (Grade 1, Unit 2; 1.MD.4)
Units on the Horizon:
 Demonstrating proficiency in addition and subtraction situations (Grade 1, Unit 18)
 Relating skip counting to mental addition and subtraction (Grade 2, Unit 8)
 Compare two twodigit numbers (Grade 1, Unit 13)
 Generating and representing measurement data to solve problems. (Grade 2, Unit 9)
Lessons

Lesson objective: Solve compare problems / More Version. Students bring prior knowledge of addition and subtraction from 1.OA.3. This prior knowledge is extended to larger numbers as students solve problems. A conceptual challenge students may encounter...

Lesson objective: Solve compare problems. This lesson helps to build fluency with solving compare problems (more version). Counters and number lines are used here because they support student understanding of comparing two groups. This work develops stu...

Lesson objective: Apply knowledge of compare problems (more version) to write and solve your own comparison problem. This lesson provides an opportunity for students to apply their knowledge and understanding of using strategies and tools to solve probl...

Lesson objective: Understand that addition and subtraction are related operations. Students bring prior knowledge of addition and subtraction from 1.OA.C.6. This prior knowledge is extended to include the relationship between the two operations as stude...

Lesson objective: Add or subtract to find the missing addend. This lesson helps to build procedural skill with solving for the missing addend. A variety of strategies and tools are used here because they support student understanding. This work develops...

Lesson objective: Solve addition and subtraction problems where both "parts" are unknown. This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a reallife situation. Students are aske...

Lesson objective: Understand that the equal sign means that there are two equivalent quantities on each side of the equal sign. Students bring prior knowledge of decomposing numbers less than 10 from K.OA.A.3. This prior knowledge is extended to numbers...

Lesson objective: Find numbers or expressions to create equivalent expressions. This lesson helps to build procedural skill with finding numbers or expressions that have a given value. Balance scales are used here because they support student understand...

Lesson objective: Find missing parts to create two equivalent expressions This lesson helps to build procedural skill with finding missing parts in order to make an equivalent expressions. Balance scales are used here because they support student unders...

Lesson objective: Apply knowledge of addition and subtraction to create two expressions that have the same value. This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction to a mathematical s...

Lesson objective: Organize, represent, and interpret data and compare the values in three categories. Students bring prior knowledge of understanding subtraction as an unknownaddend problem from 1.OA.4. This prior knowledge is extended to comparison si...

Lesson objective: Compare organized data using the relationship between addition and subtraction This lesson helps to build fluency with comparison situations in relation to data collection. Number lines are used here because they support the understand...

Lesson objective: Organize collected data and compare the categories This lesson provides an opportunity for students to apply their knowledge and understanding of comparing data from a graph to a reallife situation. Students are asked to organize the ...

Lesson objective: Compare organized data using the relationship between addition and subtraction. This lesson helps to build fluency with comparison situations in relation to data collection. Number lines are used here because they support the understan...

Lesson objective: Collect, organize, and represent data in order to compare the categories. This lesson provides an opportunity for students to apply their knowledge and understanding of comparing data from a graph to a reallife situation. Students are...