Lesson plan

# 3. Solve two-digit addition problems using place value knowledge (A)

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.A.1 http://corestandards.org/Math/Content/2/OA/A/1
teaches Common Core State Standards 2.NBT.B.5 http://corestandards.org/Math/Content/2/NBT/B/5

# 3. Solve two-digit addition problems using place value knowledge (A)

Lesson objective: Apply understanding of tens and ones to solving addition equations when the addends are decomposed into tens and ones.

This lesson provides an opportunity for students to apply their knowledge and understanding of place value to a mathematical situation. Students are asked to use their knowledge of place value to determine a strategy to solve addition problems, then compare the types of problems the strategy works with.

Key Concept students will use:

• We can add numbers within 100 using our knowledge of place value. Note: This lesson includes values to 50. Values to 100 are addressed in upcoming lessons.

Skills students will use:

• Place value understanding that ten ones equals one ten (e.g., Grade 1, Unit 2)
• Use place value to represent numbers (e.g., Grade 1, Unit 8)

Students engage in Mathematical Practice 7 as they look for and make use of structure, which is central to the work in this task. Students should identify the structure of place value in order to add or subtract within 50.

Key vocabulary:

• decompose
• sum

Special materials needed:

• place value tools as an option for student choice