Subject: Math
Grade Level: 2nd & 3rd
Note:
- This lesson is written for addition but can be adapted for subtraction.
- This lesson is written for two digit numbers but can be adapted to use three digit numbers.
- This lesson uses the traditional algorithm. Students should have a conceptual understanding of addition/subtraction before completing this lesson.
Objective:
- Students will be able to add/subtract two digit numbers with and without regrouping using the traditional algorithm.
Anticipatory Set:
- Write a two digit addition problem that requires regrouping on the board.
- Have students find the sum by using base ten blocks.
- Explain that students will be using the traditional algorithm to solve that same problem.
Instruction:
- Model writing the first number of the problem above the second number on the whiteboard. Write the + sign and draw a line below the bottom number.
- Demonstrate how to add the ones digits, regroup to the tens column, and then add the tens digits.
- Continue modeling with more problems as needed.
Guided Practice:
- Write a two digit addition problem on the board and have the students copy it onto mini-whiteboards or paper.
- Have the students solve the problem and turn their whiteboards/paper to show you their answer.
- Continue practicing problems on whiteboards/paper until students have had a fair amount of practice with the concept.
Independent Practice:
- Pass out sports trading cards to each student making sure that each student gets a card that has several two digit numbers on the back.
- Have students choose 2 two digit numbers to practice adding.
- Have the students fill in the Multi-Digit Addition Worksheet with the problems that they use. (You may want to have more than one copy of the worksheet for each student.)
Closure:
- Call on a student to write one of their problems on the whiteboard.
- Have the student explain how to solve the problem as he/she is writing on the whiteboard.
- Continue to have students share their problems with the class in this way.
Extension Ideas:
- Have students add more than 2 two digit numbers together (ex. 34+56+92=)
