2.7
Fact Families
OBJECTIVES: To determine the inverse relationship between addition and subtraction;
and to provide practice for addition and subtraction facts for sums up to and including 10.
MENTAL MATH and REFLECTS: Pose simple subtraction number story problems. Have
children share solutions.
Suggestions
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Kevin had 9 pencils and had lost 3 pencils. How many pencils does Kevin have now? 6
pencils
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June had 5 cookies and she shared 2 cookies with Juanita. How many cookies does
June have left? 3 cookies
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Denzel had $20 and spent $7. How much does Denzel have now? $13
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Diego had $35 and spent $15. How much does Diego have now? $20
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Barb scored 25 points. Dora scored 15 points. How many more points did Barb
score? 10 points
MATH MESSAGE: ALREADY DONE BY TEACHERS
Teaching the Lesson:
DISCUSSING FACT FAMILIES: Yesterday we learned about how to use addition number
sentences to write subtraction number sentences. Today we are going to use what we know
about addition and subtraction number sentences to create fact families.
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Display on the smartboard Math Master pg. 423 or Fact Family triangle made by
teacher.
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Write 6, 3, and 9 (with the large dot above the 9 or at the top of the triangle)
in the three corners. Who can describe way in ways that these three numbers
are related.
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Show children that the three numbers can be used to make additional facts
(6+3 = 9 and 3+6 = 9) and subtraction facts (9-6 = 3 and 9-3 = 6)
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These collections of facts are called Fact Families. Why do you think that they
are called fact families and not fact lists?
o
Answers will very – looking for something along the lines of: families
because they all belong together, go together, ect.
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Can someone else name three other numbers that are related by addition?
Write on the fact triangle the three numbers in each corner.
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Have different students write the fact families on white board slates.
2.7
Fact Families
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Call up 4 students to write one number sentence each on the board.
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REPEAT WITH OTHER NUMBER SETS IF NEEDED
(10 mins.) DEMONSTRATING THE USE OF +, - FACT TRIANGLES (MRB pg. 27):
Demonstrate the flashcard procedure using an actual Fact Triangle and on the board.
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Now we are going to use the fact triangles that we cut out the other day to
practice different fact families. With your partner, this is how you play.
o
Step 1 – one partner will cover one corner of the Fact Triangle with your
thumb or finger.
o
The number you cover is part of an addition or subtraction fact, the
other partner is going to complete the fact.
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A student will be called up to demonstrate with me. They will bring one of their
fact triangles up and I will write the number on the board the numbers so the
whole class can see. Then I will cover the number on both the board and actual
card. Then the student will complete the fact family.
** STUDENT WILL BE PARTNERED AS FOLLOWED (these pairings are based on ability
and how well the students with one another):
o
Ja’Noble – Lyla
o
Giselle – Devin
o
Azarria – Matthew
o
Ahmod – Zaid
o
Kaitlyn – Adam
o
Marco – Katya
o
Sarah - Oksana
o
Samantha - Kai
o
Alexa – Alissa
o
Esosa – Emily
o
Savannah – Astha
o
Johnequa – Sophi
o
Taevon – Patrick
Ongoing Learning & Practice:
SOLVING SUBTRACTION NUMBER STORIES (Math Journal 1 pg. 37):
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Change-to-less and comparison subtraction stories were covered previously in
Lesson 2.6 and practiced in the Mental Math and Reflection problems in the Lesson.
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We will as a class, we will do the first problem together and then they will do the
rest on their own.
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When student have completed Math Journal 1 pg. 37  they will continue onto pg.
38.
HOMEWORK:
2.7
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Fact Families
Home Link 2.7