Title: Adding 2-Digit Numbers within 200

Grade Level: 2nd or 3rd grade

Learning Intention: Students will be able to add two-digit numbers within 200 using various strategies.

Lesson Outline:

1. Warm-up (5 minutes):
   • Begin the lesson by reviewing the concept of place value and the value of each digit in a two-digit number.
   • Ask students to mentally solve the following addition problems: 34 + 12, 56 + 18, and 79 + 21.
   • Discuss the strategies used by students to solve the problems.
2. Introduction (10 minutes):
   • Display a number line from 0 to 200 on the board or chart paper.
   • Explain to students that they will be learning how to add two-digit numbers within 200 using different strategies.
   • Discuss the importance of understanding place value when adding two-digit numbers.
3. Strategy 1: Using Place Value (15 minutes):
   • Model how to add two-digit numbers using place value.
   • Write a two-digit addition problem on the board, such as 47 + 38.
   • Break down the problem by adding the ones place first (7 + 8 = 15) and then the tens place (4 + 3 = 7).
   • Combine the results to find the sum (70 + 15 = 85).
   • Provide additional examples for students to practice using this strategy.
4. Strategy 2: Using Base Ten Blocks (15 minutes):
   • Distribute base ten blocks or provide a virtual base ten blocks tool.
   • Write a two-digit addition problem on the board, such as 56 + 27.
   • Model how to represent each number using base ten blocks.
   • Combine the blocks to find the sum.
   • Provide opportunities for students to practice using this strategy with different addition problems.
5. Strategy 3: Using Mental Math (10 minutes):
   • Explain to students that they can use mental math strategies to add two-digit numbers quickly.
   • Demonstrate how to use compatible numbers or friendly numbers to simplify the addition.
   • Write a two-digit addition problem on the board, such as 68 + 32.
   • Encourage students to find compatible numbers (e.g., 68 + 32 = 70 + 30 + 2) and mentally solve the problem.
   • Provide additional examples for students to practice using this strategy.
6. Guided Practice (15 minutes):
   • Divide students into pairs or small groups.
   • Distribute worksheets or provide online resources with two-digit addition problems within 200.
   • Monitor and support students as they practice using the different strategies.
   • Encourage students to explain their thinking and strategies to their partners.
7. Independent Practice (10 minutes):
   • Assign independent practice worksheets or online activities for students to complete individually.
   • Circulate the classroom to provide assistance and check for understanding.
8. Conclusion (5 minutes):
   • Gather students together and review the strategies they learned for adding two-digit numbers within 200.
   • Ask a few students to share their favorite strategy and explain why they find it helpful.
   • Summarize the importance of understanding place value and using different strategies to solve addition problems.
9. Extension Activity (optional):
   • Provide challenge problems for students who finish early or need additional practice.
   • Encourage students to create their own two-digit addition problems and solve them using the strategies learned in the lesson.
   • Allow students to share their self-created problems and solutions with the class.