My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
What's the Math?
Common Core State Standards
FOCUS
Domain: Operations and Algebraic Thinking
Major Cluster: Add and subtract within 20.
Objective: Students will identify similarites in fact families.
Standards
1.OA.6Add and subtract within 20, demonstrating fluency for addition and subtraction
within 10. Use strategies such as counting on; making ten; decomposing a
number leading to a ten; using the relationship between addition and
subtraction; and creating equivalent but easier or known sums.
Mathematical Practices
1 Make sense of problems and persevere in solving them.
2 Reason abstractly and quantitatively.
3 Construct viable arguments and critique the reasoning of others.
5 Use appropriate tools strategically.
7 Look for and make use of structure.
8 Look for and express regularity in repeated reasoning.
COHERENCE
Thinking Across Grades
Previous
Now
Next
Grade K K.OA.2
Grade 1 1.OA.6
Grade 2 2.OA.2
Linking to Major Topics
Connected to the following critical area of focus: 1. Developing understanding
of addition, subtraction, and strategies for addition and subtraction within 20.
Connected to the following standards: K.OA.2, 1.OA.4, 1.OA.6, 1.OA.7, 2.OA.2
RIGOR
The exercises increase in complexity throughout the lesson.
However, individual student thinking may vary during extended processing.
Levels of Complexity
Level 1 Understand Concepts Exercises 1–3
Level 2 Apply Concepts Exercises 4–7
Level 3 Extend Concepts Exercises 8–9; Hot Problem
What Students Should Understand
Related facts make a fact family.
What Students Should Be Able To Do
Students should be able to complete a fact family when given all of the addends.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
6 + 4 = 10
4 + 6 = 10
10 – 4 = 6
10 – 6 = 4
Building on the Essential Question
In this lesson, students will build upon the skills and concepts needed to answer the chapter’s Essential
Question “What strategies can I use to subtract?”
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Developing Vocabulary / Get Ready
New Vocabulary
fact family
Activity
Have students skim the first two pages of the lesson. Ask them to point to the vocabulary word. Prompt
them by reminding them that vocabulary words are highlighted.
Ask volunteers to describe what they notice in the example near the definition. For example, they might
explain that the same 3 numbers are used in the four facts.
Reason Quantitatively What do you notice about the number at the top of the triangle?
Sample answer: It is the sum of the two addends in the bottom two corners of the triangle.
English Language Learner Instructional Strategy
Collaborative Support: Act It Out
Write the term fact family on the board. Say, A fact family is a group of four related addition and
subtraction facts that use the same three numbers.
Roll two 0–5 number cubes. Write the numbers on large cards. Create the number sentence for the
sum of those numbers and write the sum on another large card. For example 2 + 3 = 5. Say, Using
these three numbers: two, three, and five, I will create three more number sentences. Rearrange the
cards to create 3 + 2 = 5; 5 - 2 = 3; 5 - 3 = 2.
As an extension after the lesson, provide pairs of students with 3 numbers that are used in the related
facts of a fact family. Have students create three cards with the numbers, as well as one with a minus
sign, one with an addition sign and one with an equals sign. Students then model making the related
facts to complete the fact family.
For non-Spanish speaking ELLs, refer to the Multilingual eGlossary for interactive definitions in 13
languages.
My Vocabulary Cards
Discuss with students how the addition and subtraction sentences on the fact family vocabulary card
represent the definition.
Virtual Word Wall
Add this vocabulary card to the Virtual Word Wall for the chapter.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Launch the Lesson / Investigate & Model
Review
Problem of the Day
Carmen caught 10 frogs. Then some of the frogs hopped away.
There are 8 frogs left. How many frogs hopped away? 2 frogs
Use Appropriate Tools Which strategy might be helpful to solve
this problem? Sample answer: I could use a related addition fact
because I noticed that if I count up 2 from 8, I get to 10.
8 + 2 = 10 so 10 - 8 = 2.
Common Core Quick Check
Use this activity as a quick review and assessment of the previous lesson. A printable version is
available online.
Additional review occurs at the end of the chapter.
Additional Resources
Literature Connection
Read a trade book, such as The Fact Family by Sandy Turley, to prepare
students for this lesson.
Use the activity card Fact Family Dominoes after this lesson. The
Teacher Guide provides suggestions for differentiated instruction.
Investigate the Math
Target: Conceptual Understanding
Materials: Lesson Presentation slides
This investigation emphasizes mathematical reasoning.
Write an example of a fact family.
Students investigate ways to model related sums and differences.
Students come together to discuss their results and attend to precision.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Model the Math
Target: Procedural Skill and Fluency
Ask a group of three students and a group of five students to come to the front of the class and stand
opposite each other.
How can we add these groups together? Sample answer: Move the groups together.
Add the group of 3 to the group of 5.
How many students are there altogether? 8 students
How can I get the original groups back? Sample answers: Separate the groups; subtract.
Have students subtract 3 from 8. Explain that now there is a group of 3 and a group of 5 again. Repeat
the activity with other number combinations.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Teach
Explore and Explain
You will need
connecting cubes
Lead students through the steps to show a fact family for the number story.
How many fish are swimming together? seven fish
Connect that many cubes. How many fish join them? three fish
Connect that many more cubes. Write an addition number sentence to show how you would find the
number of fish there are in all. Remind students that addends can be added in any order.
Write a second addition sentence showing the number of fish in all.
Remind students that each addition number sentence has a related subtraction number sentence.
Which part of the addition number sentence goes in the first blank of the related subtraction number
sentence? the sum
Explain where to place each addend from the addition number sentence into its related subtraction
number sentence. Sample answer: One addend is the number taken away, and the other addend is the
difference.
Write the two subtraction number sentences that are related to the two addition number sentences.
When students have completed the exercise, explain that they have created the fact family for the
numbers ten, seven, and three.
Repeated Reasoning Challenge students to show the fact family if the numbers were different.
Could we still model the fact family if there were 5 fish swimming and 4 fish joined them? Yes; 5 + 4 =
9, 4 + 5 = 9, 9 - 4 = 5, 9 - 5 = 4.
See and Show
Guide students through the example at the top of the student page. Read the sentence to the class.
Explain to students how these are all related facts. Provide each student with 22 connecting cubes.
Have students model each of the addition and subtraction sentences shown in the example. Tell
students to trace the dashed numbers to show the fact family.
Work through Exercises 1-3 as a class.
Talk Math: Collaborative Conversation
Discuss with students “What fact family can you make with the numbers 4, 9, and 13?”
Sample answer: 4 + 9 = 13, 13 – 9 = 4, 9 + 4 = 13, 13 – 4 = 9
Check for Reasonableness How do you know that the sum of 4 and 9 is 13? Sample answer:
I can use subtraction to check. 13 - 9 = 4.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Practice & Apply
On My Own
Based on your observations, you may choose to assign exercises
as noted in the levels below:
Approaching Level Guide students through the exercises in On My Own. Help them to use
manipulatives while working through the exercises.
On Level Have students complete the exercises independently.
Beyond Level Have students complete the exercises independently without manipulatives.
Common Error! Students sometimes read operation signs too quickly. Encourage students to read
addition and subtraction number sentences carefully.
Problem Solving
Construct Arguments
Exercise 9 How could you justify your answer for the number of turtles still in the ocean?
Sample answer: I could use addition to check that my answer is correct.
Persevere in Solving Problems
Hot Problem How would you describe what you are trying to find?
Sample answer: I am trying to find what number subtracted from 17 is 9.
Formative Assessment
Response Cards Distribute 1 index card to each student. Challenge students to write the remaining 3
facts in the fact family once they find the missing number in the Hot Problem. 17 - 8 = 9, 17 - 9 = 8, 8 +
9 = 17, 9 + 8 = 17
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Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Differentiated Instruction
Differentiated Instruction
TIER 2: Strategic Intervention
Hands-On Activity Materials: connecting cubes, pencil and paper
Provide students with 3 numbers that make up a fact family, such as 5, 7 and 12. Invite students to use
their connecting cubes to model 2 addition facts and 2 subtraction facts using the 3 numbers given.
Have students record their facts on paper. Encourage students to repeat the activity using a set of 3
numbers from other fact families.
TIER 1
Hands-On Activity Materials: index cards, markers
Prepare fact-family flash cards ahead of time by writing one addition and one subtraction fact on each
index card. In each fact, leave out one number and put a blank in its place. Write the missing number
on the back of the card as well as the other number sentences in that fact family. Have partners use the
cards like flash cards. After naming the missing number, students can name one, or all, of the other
facts in the same family.
Extend
Hands-On Activity Materials: paper, crayons
Have students work in pairs. Have partners write and illustrate a subtraction story using facts to 20. Tell
them to write the subtraction number sentence at the bottom of their paper with the story and illustration
above it. Have students write the addition and the subtraction facts in the fact family that go with the
story. Have students repeat the activity several times using different fact families.
Differentiated English Language Learner Support
Number Sense
Show a picture of a family with parents and children. Say, This is a family. Write out a fact family. Say,
This is a fact family. Emphasize fact family. Prepare different sets of related facts on individual strips of
paper, such as 3 + 2 = 5, 2 + 3 = 5, 5 2 = 3, and 5 - 3 = 2. Distribute one strip of paper to each student.
Say, Find your fact family. Then have students find the other three students that have related facts.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Word Knowledge
Review the words: family, number fact, and fact family. Prepare a number fact, a fact family, or a
picture of a human family on numerous index cards. Shuffle and distribute one card to each student.
Have students find other students with the same type of card. Have the Number Fact Group read its
number facts. Have the Family Picture Group show its pictures and count the number of people in each
family. Have the Fact Family Group read the fact family on each card.
Developing Oral Language
Divide students into groups of four. Have one student write 13 + 8 = 21 on a piece of paper, read it
aloud, and then pass it to the next student. The next student writes another number sentence in the fact
family, for example 8 + 13 = 21, reads it aloud, and passes it onto the next student. Continue until all
facts in the fact family have been written. Repeat the activity multiple times, allowing each student to
choose the first fact to write.
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Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
Wrap It Up
My Homework
Assign homework after successful completion of the lesson. Students who understand the concepts
may skip the Homework Helper section.
Problem Solving
Use Structure
Exercises 3 Challenge students to rewrite the word problem so that it starts with the number of
flamingos Pedro sees in all. Sample answer: Pedro saw 9 flamingos at the zoo. 5 were in the water.
How many were in the grass?
Vocabulary Check
Refer students to their My Vocabulary Cards for additional support.
Formative Assessment
Example/Non Example Ask students to identify which of the following sets of numbers are not a fact
family.
4, 4, and 8
12, 7, and 2
9, 14, and 5
Have students use words or counters to explain their thinking.
Sample answer: 12, 7, and 2 because 7 + 2 does not equal 12.
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My Math, Grade 1 © 2013 / 2014
Chapter 4: Subtraction Strategies to 20
Lesson 7: Fact Families
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