Lesson plan

# 13. Solving real-world addition and subtraction problems (A)

teaches Common Core State Standards 2.OA.A.1 http://corestandards.org/Math/Content/2/OA/A/1
teaches Common Core State Standards MP1 http://corestandards.org/Math/Practice/MP1
teaches Common Core State Standards MP7 http://corestandards.org/Math/Practice/MP7
teaches Common Core State Standards 2.OA.B.2 http://corestandards.org/Math/Content/2/OA/B/2

# 13. Solving real-world addition and subtraction problems (A)

Lesson objective: Solve real world addition and subtraction comparison problems.

This lesson provides an opportunity for students to apply their knowledge and understanding of the meaning of comparison situations. Students are asked to compare the number of cubes some friends use to create structures. The friends compare the number of cubes they use and write comparison equations about their structures.

Key Concept students will use: ​

• When an addend in a situation is unknown, we can solve using either addition or subtraction.

Skills students will use:

• add and subtract within 20
• find unknown values in addition and subtraction situations using the relationship between addition and subtraction
• solving comparison word problems

Students engage in Mathematical Practice 1 (Make sense of problems and persevere in solving them) as they notice that they can use the properties of operations and the relationship between addition and subtraction to solve comparison situations. Students also engage in Mathematical Practice 7 (Look for and make use of structure) as they utilize their knowledge of number sequence when comparing two numbers using “more”, "greater", "fewer" and “less" than.

Key vocabulary:

• compare
• comparison
• equation
• fewer
• less
• part/part/whole model
• subtraction
• unknown
• value

Special materials needed:

• part/part/whole mat (optional)
• cubes or counters