Transcript
Addition Strategies That Use Doubles Facts
Objective To provide opportunities for children to explore and practice doubles-plus-1 and doubles-plus-2 facts.
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ePresentations
eToolkit
Algorithms Practice
EM Facts Workshop Game™
Teaching the Lesson Key Concepts and Skills • Practice doubles facts. [Operations and Computation Goal 1]
• Develop and practice strategies for addition that use doubles facts. [Operations and Computation Goal 1]
• Use doubles patterns to practice facts. [Patterns, Functions, and Algebra Goal 1]
Family Letters
Assessment Management
Common Core State Standards
Ongoing Learning & Practice 1 2 4 3
Playing Domino Top-It per partnership: 1 set of dominoes Partners practice addition facts.
Cutting Out Fact Triangles Math Journal 1, Activity Sheets 1 and 2 scissors 1 envelope per child Children cut out the first set of 18 Fact Triangles.
Key Activities
Math Boxes 2 5
Children identify and practice strategies for facts in which one addend is 1 or 2 more than the other addend.
Math Journal 1, p. 34 Children practice and maintain skills through Math Box problems.
Ongoing Assessment: Recognizing Student Achievement Use the Math Message. [Operations and Computation Goal 1]
Key Vocabulary
Curriculum Focal Points
Interactive Teacher’s Lesson Guide
Differentiation Options READINESS
Designing a Doubles Facts Book pattern blocks Pattern-Block Template paper and pencil Children explore doubles facts using a concrete model and create a Doubles Facts Book. ENRICHMENT
Exploring Calculator Doubles Math Masters, p. 30 calculator Children use calculators to explore the concept of doubles addition facts.
Home Link 2 5
Math Masters, p. 29 Children practice and maintain skills through Home Link activities.
doubles-plus-1 facts doubles-plus-2 facts
Materials Math Journal 1, pp. 27 and 33 Home Link 24 slate paper
Advance Preparation Before the lesson, draw a unit box on the board and fill it in with a label of your choice. Use the unit box and label for all the numbers that are not labeled in this lesson.
Teacher’s Reference Manual, Grades 1–3 pp. 195–198
116
Unit 2
Addition and Subtraction Facts
Mathematical Practices
SMP2, SMP5, SMP6, SMP8
Content Standards
Getting Started
2.OA.2, 2.OA.3, 2.NBT.9
Mental Math and Reflexes
Write all the doubles addition facts on a sheet of paper.
Pose +9 facts. Encourage children to think +10, then count back 1. Suggestions: 1 + 9 = ? 10 2 + 9 = ? 11 3 + 9 = ? 12
Math Message
9 + 5 = ? 14 ? = 9 + 6 15 ? = 7 + 9 16
1 Teaching the Lesson
Math Message Follow-Up
Home Link 2 4 Follow-Up
9 + ? = 16 7 4 + ? = 13 9 ? + 9 = 17 8
Review answers as necessary.
NOTE Remember to reserve time every
WHOLE-CLASS ACTIVITY
day to complete the number-line, attendance, calendar, temperature, and weather daily routines. See Daily Routines on page xxxv of this book and Teacher’s Reference Manual, pages 41–49.
(Math Journal 1, p. 27)
Ongoing Assessment: Recognizing Student Achievement
Math Message
Use the Math Message to assess children’s knowledge of doubles facts. Children are making adequate progress if they can correctly record all of the doubles facts. [Operations and Computation Goal 1]
NOTE Knowledge of doubles facts is important as this lesson focuses on strategies that assume quick recall of these facts. Daily chanting of the doubles will help reinforce this skill.
Ask children to turn to the Facts Table on journal page 27. Help them as needed while they check their list of doubles facts against the table. Remind children that sums of all doubles facts are even.
Discussing
Student Page Date
WHOLE-CLASS ACTIVITY
Doubles-Plus-1 Facts Doubles-plus-1 facts include those addition facts in which one addend is 1 more than the other addend (for example, 3 + 2). Write some doubles-plus-1 facts on the board; leave out the sums. Use both horizontal and vertical forms. (See page 118.)
Ask children to copy and complete the facts on their slates. See whether any children mention a strategy that makes use of doubles. Discuss the doubles-plus-1 strategy. To add numbers where one addend is 1 more than the other, double the smaller number and then add 1.
LESSON
Time
23
Addition/Subtraction Facts Table
+,-
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Math Journal 1, p. 27 EM3cuG2MJ1_U02_21_52.indd 27
1/7/11 12:31 PM
Lesson 2 5
117
Discussing
WHOLE-CLASS ACTIVITY
Doubles-Plus-2 Facts
7 +6
4 + 5 = = 9 + 8
5 +6
Doubles-plus-2 facts are addition facts in which one addend is 2 more than the other addend (for example, 6 + 4). Write some doubles-plus-2 facts on the board; leave out the sums. Use both horizontal and vertical forms. (See margin.) Ask children to copy and complete the facts on their slates. See whether any children mention a strategy that makes use of doubles. Discuss doubles-plus-2 strategies. To add numbers where one addend is 2 more than the other addend, double the smaller number and add 2.
7 +5
4 + 6 = = 9 + 7
6 +8
Some children may discover that they can change a doubles-plus-2 fact into a doubles fact by subtracting 1 from the larger addend and adding 1 to the smaller addend, for example, they might change 4 + 6 into the doubles fact 5 + 5.
Practicing Addition Strategies
INDEPENDENT ACTIVITY
That Use Doubles Facts (Math Journal 1, p. 33)
PROBLEM PRO P RO R OBL BLE B LE L LEM EM SO S SOLVING OL O LV VIN IN ING
Children practice and extend the doubles-plus-1 and doubles-plus-2 strategies and extend them to doubles-plus-3 facts.
2 Ongoing Learning & Practice
Playing Domino Top-It
Student Page Date
Time
LESSON
PARTNER ACTIVITY
Addition Facts
2 5 䉬
If you know a double, you know the 1-more and the 1-less sums. Example: If you know that 4 4 8, You know 4 5 9, And 437
1. 3 4
13
3.
7
2. 8 7
67
4.
15
6 5
11 5.
8 9
6.
17 8. 5 8
7 5
7.
9.
Domino Top-It is suggested in anticipation of Lesson 2-6, in which children use dominoes to construct subtraction facts.
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12 13
7 9
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69
10. 8 6
14
Try This 11. 8 8
89 87 13. 15 15
16 15 14 15
16 17 15 30 31 29
12. 12 12
12 13 12 11 14. 14 12
15 13
24 25 23 26 28
Math Journal 1, p. 33
118
Have partners place dominoes face down between them. Each player turns over a domino and calls out the sum of the dots on the two halves. The player with the higher sum wins and takes all the dominoes currently in play.
Unit 2 Addition and Subtraction Facts
Student Page
3
6
4
• •
ⴚ
ⴙ,
ⴙ,
ⴚ
8
•
7
7•
•
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ⴚ ⴙ,
ⴙ,ⴚ
ⴙ,
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Home Link 2 5
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3 5
(Math Journal 1, p. 34)
Mixed Practice Math Boxes in this lesson are paired with Math Boxes in Lesson 2-7. The skills in Problems 5 and 6 preview Unit 3 content.
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ⴙ,ⴚ
INDEPENDENT ACTIVITY
2
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Math Boxes 2 5
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6
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Tell children to store the Fact Triangles in envelopes in their tool kits when they are not using them. These Fact Triangles will be used in Lessons 2-7 and 2-11 through 2-13 as addition and subtraction flashcards. In Lesson 2-12, children will cut out a second set of Fact Triangles from Activity Sheets 3 and 4.
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ⴚ ⴙ,
Have children cut out the Fact Triangles from Activity Sheets 1 and 2. You might want to have them write their initials or draw a distinctive pattern on the back of each triangle. This will help children identify their individual sets.
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ⴙ, ⴚ Fact Triangles 1
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(Math Journal 1, Activity Sheets 1 and 2)
Time
LESSON
3
INDEPENDENT ACTIVITY
5
Cutting Out Fact Triangles
Date
h
Math Journal 1, Activity Sheet 1
INDEPENDENT ACTIVITY
(Math Masters, p. 29)
Home Connection Children complete a page of addition facts and draw a path from the child to the ice-cream cone by connecting sums of 9, 10, or 11.
Student Page Date
Home Link Master Name
Time
LESSON
2 5 䉬
Math Boxes
䉬
2. Circle the activity that takes
your math journal? Fill in the circle next to the best answer. rhombus
B
rectangle
about 1 second.
Reading a story.
C triangle D square
Family Note
Help the child find the ice-cream cone. Answer all the problems. Then draw the child’s path by connecting facts with sums of 9, 10, or 11. You can move up, down, left, or right as you move between boxes. 2 6
2 5
1 6
0 8
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3 9
7 0
4 4
1 5
4 3
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6 5
1 7
3 5
6 3
1 8
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2 4
3 3
8 7
4 4
5 4
9 3
0 9
4 6
7 1
5 5
8 0
5 9
6 7
6 1
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3 8
7 4
9 2
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2 9
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4 2
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3 9
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6 4
52
3. Complete the fact family. Fill in
the missing domino dots. 8
7 7
7
15
8 15 15 8
8 15
7 25
5. Put the numbers in order from
4. How likely is it that our school
will have a fire drill today? Circle your answer.
9
certain
Answers vary.
likely
8
unlikely impossible 6. Draw hands to show 8:15.
smallest to largest. Circle the middle number. 11 10
48, 44, 37, 54, 39
12
2 3
9
37 , 39 , 44 , 48 , 54 46
Math Journal 1, p. 34
8
4 7
6
5
8
7
1
For homework, your child will review addition facts like the ones we have been working on in class. To help identify the path from the child to the ice-cream cone, have your child circle the sums of 9, 10, and 11. Please return this Home Link to school tomorrow.
Blinking your eyes. Writing your name.
Time
Addition Facts Maze
25
1. What shape is the cover of
A
Date
HOME LINK
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Math Masters, p. 29
Lesson 2 5
119
Teaching Master Name
Date
LESSON
Time
3 Differentiation Options
Calculator Doubles
25 䉬
You can program the calculator to solve doubles problems. 1. First clear your calculator. 2. Enter
,
,
,
. (The calculator will display a 4).
Do NOT clear your calculator again while you work on this page. 3. Guess what the sum is for double 6 (6 + 6). 4. Now enter
and press
5. Guess what the sum is for double 9 (9 + 9). 6. Now enter
and press
12
. What does the calculator display?
12
18
. What does the calculator display?
18
READINESS
Designing a Doubles
INDEPENDENT ACTIVITY 15–30 Min
Facts Book
7. Make up your own doubles problems for the calculator to
solve. Record your number sentence and the sum the calculator displays. Example:
Sample answers: 7 7 14 8 8 16 6 6 12
5 5 10 Try This 8. Why do you think you entered
on the calculator to
program it to solve doubles problems?
Sample answer: I think each X shows 2 more times. So you keep adding the given number that many times.
Math Masters, p. 30
To explore doubles facts using a concrete model, have children design a Doubles Facts Book using their Pattern-Block Template. First, have children create a doubles fact using pattern blocks of the same shape. Next, children copy the design onto a sheet of paper using their template. Each design shows a doubles fact accompanied by a number model. Staple the pages together to create a Doubles Facts Book. In addition to having children describe their “double” designs using color and shape words, have them identify the sum as odd or even. For example, “There are three sides on each green triangle. I have two green triangles. Three plus three equals six. There are six sides in my design. Six is an even number.” “There are two red trapezoids and two yellow hexagons. Two plus two equals four. There are four shapes in my design. Four is an even number.” Ask children what they notice about the sums of the doubles facts. Sample answer: They are even. Have a volunteer explain why the sums of doubles facts are even. Sample answer: When 2 even numbers or 2 odd numbers are added together, the sum is always even because you will always have pairs. ENRICHMENT
Exploring Calculator Doubles
PARTNER ACTIVITY 5–15 Min
(Math Masters, p. 30)
To further explore the concept of doubles addition facts, have children work with a partner to solve “doubles” problems on a calculator.
120
Unit 2 Addition and Subtraction Facts
