Lesson: Relating Addition and Subtraction

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Lesson Objective

Students will explore the relationship between addition and subtraction.

Lesson Plan

Do Now:


Focus students attention on the question: How are addition and subtraction related?

Directed Instruction (15 min):

 
  • State the objective.
  • Give each student a paper plate. Ask the students to fold their paper plate in half. Tell them to put four counters on one side and two counters on the other side. Have the students write the number of pieces on each side, and then cover one side. Ask what subtraction sentence they could write to describe the "take away" situation. Have them repeat the exercise by covering the other side. Then ask what addition sentences describe how the two sets can be joined. Finally, ask the students to write the four sentences these two sets suggest. 4 + 2 = 6; 2 + 4 = 6; 6 – 2 = 4; 6 – 4 = 2.
  • Now put 4 on one side of their plates and zero pieces on the other side. Call on a volunteer to tell each of the appropriate subtraction and addition stories. Then call on another student to write  the two addition and subtraction sentences on the white/chalkboard.

 

Independent Practice (15 min): 


 
  • Distribute counters to pairs of students and have them take turns making two sets, covering one group of counters, and writing number sentences. Then call the students together and ask a volunteer to make two sets and write the four number sentences (two addition and two subtraction) that the sets of counters suggest. You may wish to repeat this with other volunteers. Invite one of the students to make two sets, each with five counters, and write the related addition and subtraction sentences.  Finally, ask the students to write the set of number sentences that would be appropriate if one set had six counters and the other had zero.
  • Tell the students that you are thinking of a piece of paper that has eight counters in all, and two are on the left side. Ask them to determine how many are on the right side of the paper. Invite the students to consider the equation: 2 + _ = 8. Remind students that eight is the sum and that the other two numbers are addends. Ask: What is the missing addend? Six.Repeat with other examples.
     
  • Closing (5 min): 

 

  • Ask the students to write one of the examples and to illustrate it with a picture.

Lesson Resources

Relating Addition and Subtraction IP   Classwork
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