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Title: Unit 2, Lesson 1


1
Unit 2, Lesson 1
  • Addition Facts Strategies

2
Goals
  • Commutative and associative properties of
    addition
  • Practice addition facts strategies

3
What We Will Learn Today
  • We are going to learn that we can add numbers in
    any order and still get the same answer.
  • That can group numbers together any way we want
    when we add.
  • It is easier to add numbers when you make groups
    of ten.

4
Using a Ten
  • You will work in pairs.
  • Each pair will have 40 connecting cubes.
  • Materials getters, please get a bag of cubes and
    give 4 trains of 10 to each pair in your group.
    Please make sure that they have four different
    colors.

5
Using a Ten
  • You have enough cubes for you to do some of these
    activities on your own.
  • Some of the activities will require that you work
    together with your cubes.

6
Using a Ten
  • I want each student to take two different colors
    of connecting cubes.
  • Build one train with 7 cubes of one color.
  • Building another train with 8 cubes of another
    color.

7
Using a Ten
  • What can you do with your cubes to make a train
    of ten?
  • Yes, move two cubes from the train of seven cubes
    to the train of eight cubes.
  • Or, move three cubes from the train of eight
    cubes to the train of seven cubes.

8
Using a Ten
  • You now have a train of 10 cubes and a train of 5
    cubes. What is the sum?
  • 15
  • Why is this problem (10 5) easier to solve than
    the first one (7 8)?

9
Vocabulary
  • Addend a number that is added to another
  • Sum the answer to an addition sentence

10
Teaching the Activity
  • Do the following problems by making a train of
    one color for the first addend and a train of
    another color for the second addend.
  • 6 7
  • Why is 10 3 easier to solve than
  • 6 7?

11
Teaching the Activity
  • 8 8
  • Why is 10 6 easier to solve than 8 8?

12
Teaching the Activity
  • 8 9
  • Why is 10 7 easier to add than 8 9?

13
Switch It!
  • These next problems you will have to do in pairs.
  • Solve 14 7 6 with connecting cubes. Use a
    different color for each addend.
  • Group the cubes in as many tens as possible.

14
Switch It!
  • What can you do with the train of 14?
  • What can you group together to make a ten?
  • What is your answer?

15
Switch It!
  • Lets share your solutions.

16
Challenge
  • Try to add 14 7 6 using mental arithmetic.
  • See if you can rearrange any of the numbers to
    make groups of ten.
  • How did you solve this without paper, pencil or
    cubes?

17
More Problems
  • Do these problems first with mental addition.
    Try to find groups of 10. You may also use
    doubles.
  • Then use your cubes.
  • 8 7 12
  • 6 8 14
  • 11 3 9

18
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19
Vocabulary
  • Partition To divide into parts.
  • Ex 7 can be divided into 5 and 2

20
Breaking Addends into Parts
  • Sometimes addends can be easily grouped into
    tens.
  • Sometimes this isnt easy to see.
  • Try partitioning addends before finding groups of
    ten.

21
Breaking Addends into Parts
  • Example 7 5 2
  • The second addend, 5, can be rewritten as 3 2.
  • 7 3 2 2
  • What two numbers can you group together to make
    10?
  • What is the sum?

22
Breaking Addends into Parts
  • Work with your partners to solve the following
    problems.
  • Use your math notebook to write the number
    sentence and then show how you partitioned the
    number.

23
Breaking Addends into Part
  • 6 8 3
  • 9 7 2
  • 4 9 3
  • Lets compare your solutions.

24
My Calculator is Broken
  • We are going to imagine that some of the keys on
    the calculator are broken.
  • That means that you cannot use those keys.
  • .

25
My Calculator is Broken
  • First, lets imagine the five is broken.
  • What keys would you press to do the problem 9 5
    2?
  • Share your solutions.

26
My Calculator is Broken
  • Do these additional problems without using the 5
    key.
  • 8 5
  • Share your solutions
  • 5 7 6
  • Share your solutions

27
My Calculator is Broken
  • 15 6 3
  • Share your solutions
  • 9 25
  • Share your solutions

28
What We have Learned
  • We learned that we can add numbers in any order
    and still get the same answer.
  • We can group numbers together any way we want
    when we add.
  • It is easier to add numbers when you make groups
    of ten.
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