Illuminations: Do It with Dominoes

Do It with Dominoes

Finding Fact Families

In this lesson, the relationship of subtraction to addition is introduced with a book and with dominoes. Then students explore the concept of missing addends.

Learning Objectives
 
Students will:
  • find missing addends
  • review the additive identity
  • relate subtraction to addition

Materials
 
Book: Ten Sly Piranhas, by William Wise
Dominoes
Index cards

Instructional Plan

To review the concept of subtraction, read Ten Sly Piranhas. Ask the children to act out with counters what is happening in the story and to write the related subtraction sentence for each page. Then call out a sum and have each child show you a domino with that many spots. Encourage the students to write the addition equation suggested by the domino.

 

 

In the example above, students may sugggest the following addition equation:

6 + 4 = 10

 

Next, choose two dominoes with the same number of total spots, then display them with one crossed over the other so that both parts of the upper domino but only one part of the bottom domino is visible. Now tell the children that both dominoes have the same number of spots and that they are to guess how many spots are covered on the bottom domino. When a correct response is given, display the domino and ask the students to explain how they knew.

Model the activity a few more times, being sure to include one example of what happens when one domino has 0 spots on one side. Then place the students in pairs and have them take turns being the teacher. This activity will help them focus on the relationship of subtraction to addition. Finally, ask the pairs to sort the set of Double 6 dominoes by the sums that the dominoes represent. Ask the students to write a sentence about this exercise for their portfolios.

Now call the children together and ask a volunteer to choose a domino that is not a double and write the four number sentences (two addition and two subtraction) that the domino suggests. You may wish to repeat this exercise with other volunteers.

 

 

For the domino above, the following addition and subtraction sentences are suggested:

4 + 5 = 9
5 + 4 = 9
9 - 5 = 4
9 - 4 = 5

As the lesson concludes, remind the students that they need to practice the addition facts and that making more triangle-shaped flash cards will help them to do so.

Questions for Students
 

What is missing when I say “2 + ‘something’ = 5?” Can you write the complete addition sentence?

[3 is missing; 2 + 3 = 5]

What about when I say “6 + ‘something’ equals 6?” What addition sentence would show that?

[0 is missing; 6 + 0 = 6]

What addition and subtraction facts can I write if I pick a 3+4 domino? Suppose I pick a 3+0 domino? A 3+3 domino?

[Answers may include any of the following:
3 + 4 = 7
7 - 4 = 3
3 + 0 = 3
3 - 0 = 3
3 + 3 = 6
6 - 3 = 3]

How could you help a friend find a subtraction fact related to 5 + 4 = 9?

[Student responses may vary, but they may say 9 - 4 = 5]

Assessment Options
 
  1. The Questions for Students help students focus on their current level of understanding and of fact mastery.
  2. You may wish to add more documentation to the Class Notes chart. These notes will be valuable as you plan appropriate remediation and enrichment opportunities.

Teacher Reflection
 
  • Which students have some of the facts memorized?
  • Did most students remember the effects of adding by 0? Did most recall the order property?
  • Which students met all the objectives of this lesson? What extension activities are appropriate for those students?
  • Which students are still having difficulty with the objectives of this lesson? What additional instructional experiences do they need?
  • What will you do differently the next time that you teach this lesson?

NCTM Standards and Expectations
 
Number & Operations Pre-K-2
  1. Develop and use strategies for whole-number computations, with a focus on addition and subtraction.
  2. Understand the effects of adding and subtracting whole numbers.
  3. Understand various meanings of addition and subtraction of whole numbers and the relationship between the two operations.
  4. Develop fluency with basic number combinations for addition and subtraction.
  5. Use a variety of methods and tools to compute, including objects, mental computation, estimation, paper and pencil, and calculators.

References
 
  • Wise, William. Ten Sly Piranhas. New York: Dial, 1993.
This lesson prepared by Grace M. Burton.
  
1 period   

NCTM Resources

Principles and Standards for School Mathematics
National Council of Teachers of Mathematics Thinkfinity Verizon Foundation
More and Better Mathematics for All Students
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