Lesson plan

# 15. Creating and solving comparison 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

# 15. Creating and solving comparison problems (A)

Apply understanding of addition and subtraction situations to create compare story problems.

This lesson provides an opportunity for students to apply their knowledge and understanding of addition and subtraction comparison situations to a real-life situation. Students are asked to create a compare addition or subtraction story problem and to solve a friend's problem using pictures and equations.

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 using the number line. 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”, "fewer", and “less" than.

Key vocabulary:

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

Special materials needed:

• part/part/whole mat
• cubes or counters