Grade 1: Unit 1.OA.C.5-6, Add and subtract within 20
Lesson Seed:Counting by 2’s to Add or Subtract(Lesson seeds are ideas for the domain/cluster/standard that can be used to build a lesson.Lesson seeds are not meant to be all-inclusive, nor are they substitutes for instruction.)
Domain:1.OA - Operations and Algebraic ThinkingCluster:Add and subtract within 20
Standard(s):1.OA.C.5Relate counting to addition and subtraction (e.g., by counting on 2 to add 2).
Purpose/Big Idea:Students relate counting on to addition and counting back to subtraction
Materials:
- Large Hundred Chart
- Resource Sheet 1: Hundred Chart (one per student)
- Resource Sheet 2: Equation Recording Sheet
- Counters to use on Hundreds Chart
- Resource Sheet 3: Add 2 or Subtract 2 Spinner
Activity: Addition
- Display a large Hundred Chart. Circle the number 6.
- Ask the students “If we started at ‘6’ and counted on by 2 where would we land?”
- Ask students “What equation could we write for what we just did? (Student Response should be: 6 + 2 = 8.
- Repeat this a few times with different starting numbers.
- Distribute to each student
- Resource Sheet 1 Hundred Chart
- Resource Sheet 2: Equation Recording Sheet
- Counters or snap cubes
- Ask students to place a counter on their Hundred Chart and then count on by 2 and record the equation that represents this move.
- Discuss the fact that counting on by two is just like adding two.
- Allow time for students to repeat this several times with various starting numbers.
- Gather students together and have them model on the Class Hundreds Chart some of the equation they recorded.
- Allow student to explore counting on by other numbers, such as 5, 3, or 4. What do they notice about their equations?
- Repeat the activity above but ask students to count back by 2’s and record their equations for subtraction.
- Allow time for students to share their equations and explain how they know they are correct using the Class Hundred Chart.
- Distribute
- Resource Sheet 1 Hundred Chart to each student
- Resource Sheet 3: Add 2 or Subtract 2 Spinner to each pair of students.
- Paperclip to use as spinner
- Pencil to hold paperclip in place
- Counters for students to use a pawns in the game
- Explain that the pairs of students are to play a game in which they spin the spinner and move back and forth on the Hundred Chart depending of if they land on ‘Add 2’ or ‘Subtract 2’. The first player to reach 100 wins the game.
Guiding Questions:
- How did you use you’re theHundred Chartto help you create equations for addition or subtraction?
- What other math tools could you use (number line, counters, mental math)?
- What strategies can you use to figure out what equation to write?
- How many different equations could you write to show this?
- How might you use these strategies to solve math problems in your everyday life?
May 16, 2013 Page 1 of 7
Grade 1: Unit 1.OA.C.5-6, Add and subtract within 20
Resource Sheet 1 Hundred Chart
1 / 2 / 3 / 4 / 5 / 6 / 7 / 8 / 9 / 1011 / 12 / 13 / 14 / 15 / 16 / 17 / 18 / 19 / 20
21 / 22 / 23 / 24 / 25 / 26 / 27 / 28 / 29 / 30
31 / 32 / 33 / 34 / 35 / 36 / 37 / 38 / 39 / 40
41 / 42 / 43 / 44 / 45 / 46 / 47 / 48 / 49 / 50
51 / 52 / 53 / 54 / 55 / 56 / 57 / 58 / 59 / 60
61 / 62 / 63 / 64 / 65 / 66 / 67 / 68 / 69 / 70
71 / 72 / 73 / 74 / 75 / 76 / 77 / 78 / 79 / 80
81 / 82 / 83 / 84 / 85 / 86 / 87 / 88 / 89 / 90
91 / 92 / 93 / 94 / 95 / 96 / 97 / 98 / 99 / 100
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Grade 1: Unit 1.OA.C.5-6, Add and subtract within 20
Resource Sheet 2 Equation Recording Sheet
Name______Date______
Resource Sheet 3 Add 2 or Subtract2 Spinner
May 16, 2013 Page 1 of 7