grade 2: 2.oa.b.2, add & subtract within...

Grade 2: 2.OA.B.2, Add & Subtract within 20

Lesson Plan: Addition & Subtraction Mental Strategies (This lesson should be adapted, including instructional time, to meet the needs of your students.)

Background Information

Content/Grade LevelMathematics/Grade 2 Domain: 2.OA-Operations and Algebraic Thinking Cluster: 2.OA.B Add and subtract within 20

Unit/Cluster: Add and subtract within 20

Essential Questions/Enduring Understandings Addressed in the Lesson

How do I know which mathematical operations to use? What are different ways to count? What are the most efficient ways to count? In what ways can numbers be composed and decomposed? What questions can be answered using addition and/or subtraction?

There are many ways to represent a number. There are different strategies that can be used to solve a problem, but some are more effective

and efficient than others. The ability to solve problems is the heart of mathematics. Number sense develops through experience Operations create relationships between numbers. The relationship among the operations and their properties promote computational fluency.

Standards Addressed in This Lesson

2.OA.B.2: Fluently add and subtract within 20 using mental strategies. By end of Grade 2, know from memory all sums of two one-digit numbers.

Lesson Topic Addition and Subtraction Mental Strategies

Relevance/ConnectionsIt is critical that the Standards for Mathematical Practice are incorporated in ALL lesson activities throughout the unit as appropriate. It is not the expectation that all eight Mathematical Practices will be evident in every lesson. The Standards for Mathematical Practice make an excellent framework on which to plan your instruction. Look for the infusion of the Mathematical Practices throughout this unit.

Student Outcomes Students will apply Level 2 & 3 strategies such as Counting On, Recomposing Addends, and Doubles ± a number when adding and/or subtracting.

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Demonstrate fluency for addition and subtraction within 20.

Prior Knowledge Needed to Support This Learning

Students in Grade 1 work with addition and subtraction within 20 to solve word problems. Students in Kindergarten understand addition as putting together and adding to, and understand

subtraction as taking apart and taking from.

Method for determining student readiness for the lesson

Formative assessment where students solve story problems using addition and subtraction strategies.

Learning Experience

Component DetailsWhich Standards for Mathematical Practice(s) does this address? How is the Practice used to

help students develop proficiency?Warm Up Materials Needed:

Resource Sheet 1: Riding the Bus

Directions: Distribute a copy of Resource Sheet 1: Riding the

Buss to each student. Allow time for students to work independently on the

task. Gather students together and have them share the

different equations they recorded. Record their equations on chart paper. Ask students if we have found all of the possible

combinations of boys and girls. How would we know?

SMP 1: Make sense of problems and persevere in solving them. – Students determine all the possible combinations of boys and girls that could be on the bus.

SMP 2: Reason abstractly and quantitatively. – Students reason quantitatively to determine the correct equations to record.

SMP 4: Model with mathematics. – Students model with mathematics by recording correct equations.

Motivation Ask students, “What different strategies did you use to solve the ‘Riding the Bus’ problem?

Allow time for students to share their strategies and ideas, asking them to ‘act them out’ for the class.

Make a list of all the strategies that students employed, noting for upcoming instruction missing strategies that could be focused on during instruction.

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Learning ExperienceActivity 1

UDL Components Multiple Means of

Representation Multiple Means for

Action and Expression

Multiple Means for Engagement

Key QuestionsFormative AssessmentSummary

Students will use the Double Ten Frame Work Mat, the Making ten Recording Sheet, and Snap Cubes to explore the Making Ten strategy for addition.

UDL Components Representation is present in the activity through the

use of the recording sheet, snap cubes, and double ten frames. Virtual manipulatives are offered when available (i.e., Online number generator).

Expression is present in the activity through choices offered in how students record their solutions.

Engagement is present in the activity through the use of a task that allows for active participation and exploration.

Materials Needed: Resource Sheet 2: Spinners Resource Sheet 3: Double Ten Frame Work Mat Resource Sheet 4: Making Ten Recording Sheet

(several copies per student) Set of 20 snap cubes per student (with 10 of one

color and 10 of another color) Two crayons per student to match the color of the

cubes

Directions: Distribute Resource Sheet 2, 3 and 4 along with a set

of snap cubes to each student. Model using the spinner and work mat to solve an

addition problem using the ‘Make Ten’ strategy. Spin each spinner and record the numbers landed on

as the two addends in an equation on Resource Sheet 4 Making Ten Recording Sheet.

SMP 1: Make sense of problems and persevere in solving them. – Students determine solutions by using the Making Ten Strategy on the Double Ten Frames.


SMP 4: Model with mathematics. – Students model with mathematics by recording correct equations.

SMP 6: Attend to precision. – Students are accurately recording equations for the different problems and modeling using the Double Ten Frames and snap cubes.

SMP 7: Look for and make use of structure. – Students are using the double ten frames to apply the Making Ten Strategy in addition.

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Learning Experience Using the snap cubes build a rod for each number

For example, if the numbers spun are 9 and 3, build a rod of 9 in one color of snap cubes and a rod of 3 in the other color. Lay them at the top of the Double Ten Frame Work Mat.

Then place the 9 rod on the first ten frame with the first five cubes in the top row and the next 4 in the bottom row.

Ask the student what we should do now to complete the ten frame?

As students suggest, add one of the cubes from the ‘3’ rod to the first ten frame to complete it and lay the remaining two cubes from the ‘3’ rod on the second ten frame.

Model coloring in the two ten frames on the Recording Sheet to match the cubes layed on the Work Mat.

Ask the students what numbers we would use to complete the first blank equation on the Recording Sheet: ___ + ___ = ___ + ___. Their response should be 9 + 3 = 10 + 2.

Then ask what the second equation could be: (9 + 3 = 12).

Ask the students what made it easy to get the answer. Allow time for them to discuss the fact that by making a ten from the numbers spun, it was easy to see how much more was left and what the answer would be.

Allow time for the students to use the spinner, cubes, Work Mat, and Recording Sheet to explore making tens to find a sum.

Make sure they record their equations on the Recording Sheet and that they color in the ten frames on the Recording Sheet to match the cubes on the Work Mat for each problem created.

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Learning Experience Pull the class together and allow time for them to

share examples of problems they solved using the ‘Make Ten’ strategy.

Activity 2

UDL Components Multiple Means of

Representation Multiple Means for

Action and Expression

Multiple Means for Engagement

Key QuestionsFormative AssessmentSummary

Using “Ravens and Redskins” game board, students will discover when to use the “Make 10” strategy to subtract.

UDL Components Representation is present in the activity through the

use of the “Ravens and Redskins” game board and use of double ten frames. Virtual manipulatives are offered when available (i.e., Online number generator or spinner).

Expression is present in the activity through choices offered in how students record (game board or double ten frames).

Engagement is present in the activity through the use of a task that allows for active participation and exploration

Materials Needed: Resource Sheet 3: Double Ten Frame Work Mat Resource Sheet 5: Redskin vs. Ravens Game Board Resource Sheet 6: Redskins Recording Sheet Resource Sheet 7: Ravens Recording Sheet Resource Sheet 8: Digit Cards 9-20 (run on one color

paper) Resource Sheet 9: Digit Cards 1-10 (run on another

color paper) Optional: Use a 10-Sided Number cube in place of

the Digit Cards Snap Cubes or counters for use on the Work Mat, if

desired.

SMP 1: Make sense of problems and persevere in solving them. – Students determine the solutions to the problems using the Making Ten Strategy and the number line.


SMP 4: Model with mathematics. – Students model with mathematics by recording correct equations and the number line.

SMP 6: Attend to precision. – Students are accurately recording equations for the different problems.

SMP 7: Look for and make use of structure. – Students are using the number line to apply the Making Ten Strategy in subtraction.

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Learning Experience

Directions: The object of this game is for the Ravens or Redskins

helmet to reach the end zone at the end of the game board first.

Players will choose to be either Ravens or Redskins.

Players will take turns, drawing a card and then rolling the dice or drawing a digit card.

Find the difference of the 2 numbers using the number line to employ the ‘Make Ten’ strategy for subtraction. (For 17 – 5, jump backwards on the number line from 17 to 7. Then jump two individual steps backwards to get to 5. So 17 – 5 is 17 – 10 and then 7 – 2 which lands you on 5.)

Move to an adjacent space on the game board that displays that solution to your problem (forward or backward).

Record the equation and the movement on the number line (on either the Redskins Recording Sheet or the Ravens Recording Sheet depending on the team you are playing for.

If the difference is not on the board, players may move to a free space (Football Official).

To tackle/take the opposing player and knock the opposing player out of the game, land on the same space their helmet is on.

The game ends when a Raven or Redskin reaches

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Learning Experiencethe end zone.

Formative Assessment Students’ recordings should accurately show “Making

10” to subtract using a number line.

Closure Materials Needed: Resource Sheet 10: Exit Ticket

Directions: Distribute Resource Sheet 10: Exit Ticket to each

student and allow time for them to recording their responses.

Collect and review to guide future instruction.

Supporting InformationInterventions/Enrichments

Special Education/Struggling Learners

ELL Gifted and Talented

Work with struggling students in a guided activity using the snap cubes and double ten frames to help develop their conceptual understanding with the Making Ten strategy.

Allow students to work in pairs to complete the activities, discussing their thinking as they progress.

Allow students who are ready to create story problems that require the use of the Making Ten Strategy to be shared in centers or with pairs of students.

Materials Resource Sheet 1: Riding the Bus Resource Sheet 2: Spinners Resource Sheet 3: Double Ten Frame Work Mat Resource Sheet 4: Making Ten Recording Sheet Set of 20 snap cubes per student (with 10 of one color and 10 of another color) Two crayons per student to match the color of the cubes Resource Sheet 5: Redskin vs. Ravens Game Board Resource Sheet 6: Redskins Recording Sheet Resource Sheet 7: Ravens Recording Sheet

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Resource Sheet 8: Digit Cards 9-20 (run on one color paper) Resource Sheet 9: Digit Cards 1-10 (run on another color paper) Optional: Use a 10-Sided Number cube in place of the Digit Cards Snap Cubes or counters for use on the Work Mat, if desired. Resource Sheet 10: Exit Ticket

Technology Virtual manipulatives, if available

Resources(must be available to all stakeholders)

See Unit resource link

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Resource Sheet 1 Riding the BusName __________________________

10 students are riding the bus to school. Some students are boys and some are girls. Write all the different possible combinations of boys and girls riding the bus.

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7 8

9

8 7

9

8 3

7

6 5

4


Resource Sheet 2 Spinners

Resource Sheet 3 Double Ten Frame Work MatJuly 13, 2013 of 19


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Resource Sheet 4 Making Ten Recording Sheet

Equation 1:

_____ + _____ = _____ + _____

Equation 2:

_____ + _____ = _____

Equation 1:

_____ + _____ = _____ + _____

Equation 2:

_____ + _____ = _____

Equation 1:

_____ + _____ = _____ + _____

Equation 2:

_____ + _____ = _____

Equation 1:

_____ + _____ = _____ + _____

Equation 2:

_____ + _____ = _____

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Resource Sheet 5 Redskins vs. Ravens Game Board

1 2 3 40 3 1 4 2 0 55 0 1 2 6 4 24 6 2 3 0 5 10 2 3 1 0 4 55 0 3 2

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R E D S K I N S

0 2010

______ - ______ = ______

0 2010

______ - ______ = ______

0 2010

______ - ______ = ______

0 2010

______ - ______ = ______


Resource Sheet 6 Redskin Recording Sheet

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R A V E N s

0 2010

______ - ______ = ______

0 2010

______ - ______ = ______


Resource Sheet 7 Ravens Recording Sheet

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Resource Sheet 8 Digit Cards 9 – 20

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9 10 11 12

13 14 15 16

17 18 19 20

Resource Sheet 9 Digit Cards 1 – 10

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1 2 3 4

5 6 7 8

9 10

Resource Sheet 10 Exit Ticket

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Name ___________________

Explain how ‘Making Ten’ can help you solve addition and subtraction problems.

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grade 2: 2.oa.b.2, add & subtract within...

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