2.OA.B.2 - About the Math, Learning Targets, and Increasing Rigor

Grade 2 Number Operations

2.OA.B.2

About the Math
Instructional Tasks
Independent Work
Assessment

Full Standard

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

Measurement Topic

This standard is reported on the report card in these quarters as follows:

**3rd Grade Students Learning 3rd Grade Standards**
Quarter 1	Quarter 2	Quarter 3	Quarter 4
Report Card Measurement Topic: Demonstrates understanding of addition and subtraction.

About the Math

Skills and concepts below are learning goals for this standard.

Recall facts that add and subtract within 20.

This standard is a continuation of basic fact instruction started in first grade. Instruction in basic facts should focus on making sense, using strategies for remembering facts, and seeing relationships. Students need to understand the relationship of addition and subtraction as well as the commutative property. When students see the relationships such that 3 + 5 = 8 and that 5 + 3 = 8, they lessen the number of facts that need to be learned.

Use mental strategies to recall a fact when a fact can't be recalled quickly.

Recalling basic facts takes time. Instant recall of the basic facts varies from child to child. Strategies, or ways of thinking about facts, are useful for recalling facts. They are more efficient than consistently drawing or using physical models. They also hope students see patterns.

Screenshot 2024-02-21 at 9.41.08 AM.png — Description of Addition and Subtraction Basic Facts Strategies Links to an external site.

The sequence of strategy instruction in grade 2 is

Revisit strategies from grade 1 (quarter 1)
Using Ten (facts that make a ten and have some more, eg. 9 + 5, 8 + 5, 14 - 9, etc)
Using Doubles (facts that use the doubles strategy, eg 5 + 4, 9 - 5)
Work with all facts (mixed review, connection and/or extension of strategies)

The use of timed tests is discouraged as a method of learning. Timed tests are only appropriate after students have indicated that they know the facts. Use of timed-assessments should not occur more than once every three to four weeks. Basic facts allow students to be accurate and efficient in computation and mental math.

Essential vocabulary for this standard includes: Doubles, Make ten, Near doubles, sum, difference, added, count-on, count-back, think addition, strategy, part, total, subtract, add, pattern, addition, and subtraction.

Progression of Standard within Grade 2

This progression informs how to develop the standard within the grade level. This progression is provided by HCPSS Elementary Mathematics.

Progression Throughout Year
Quarter 1	Quarter 2	Quarter 3	Quarter 4
Recall facts that add and subtract within 20. Use mental strategies to recall a fact when a fact can't be recalled quickly. Review grade 1 facts: +/- 0, 1, 2; make ten; +/- 10; doubles	Recall facts that add and subtract within 20. Use mental strategies to recall a fact when a fact can't be recalled quickly. Using Ten (Make Ten and Some More) (i.e. 8 + 5 = 13, 9 + 6 = 15)	Recall facts that add and subtract within 20. Use mental strategies to recall a fact when a fact can't be recalled quickly. Using doubles (Near Doubles) (i.e. 5 + 6 = 11, 8 + 7 = 15)	Recall facts that add and subtract within 20. Use mental strategies to recall a fact when a fact can't be recalled quickly. All facts

Progression of this Standard Across Grades

This progression is informed by the Achieve the Core Coherence Map Links to an external site.. Information is not the complete standard.

Progression Across Grades
Grade 1	Grade
Fluently add and subtract within 10 (1.OA.6)	This concept is not taught after grade 2. Students are expected to apply the standard proficiently.

TASKS

These tasks can be used with small group or whole group instruction.

(doubles) Students have a set of digit cards or ten sided dice. Players draw a card or roll the dice. Whatever the number is, they double it and write the equation in their journal.
(making 10) Take a deck of playing cards and remove the face cards. The Aces become one. Play Go Fish with students however this version a pair are two cards that make ten. So if you have a 2 you would wish for an 8 to make ten.
(making 10) Each time the teacher says a number between 0 and 10, the students will use their fingers to show how much more to make ten. Students can say and/or write the math fact.
(using ten) Distribute double ten frames and 20 red and yellow counter to each student. Pose a problem such as I have 9 rocks and found 8 more. Have them build each number on the double ten frame. Then ask how many rocks do I have? If a student moves a counter to make ten, have them share their strategy. If no one does, talk the class through the strategy.
(using ten) Distribute double ten frames and 20 red and yellow counter to each student. Pose a problem such as how can i figure out 15 - 8? Have students build 15 and then take 8 away. If you observe a student taking away 5 and then 3 more, highlight their strategy. If no one does, talk the class through the strategy.
(using doubles) Distribute double ten frames and 20 red and yellow counter to each student. Pose a problem such as I have 6 stickers and Jillian gave me 7 more. Have them build each number on the double ten frame. Then ask how many stickers do I have? If a student talks about how they see 6 + 6 +1 have them share their strategy. If no one does, talk the class through the strategy.
(using doubles) Students take a doubles flash cards and builds both numbers using using snap cubes. Discuss with the students how one tower is one taller than the other tower. In their journals, have students write the equation in their journal.
(making 20) Beth had a pack of 20 pencils. The pencils were two different colors. Show all the combinations of pencils she could have that equal 20. Draw pictures and write equations to support your answer.
(use of strategies) Pull out a variety of flash cards (or dominoes) from different strategies. Write the names of strategies on note cards, such as using ten and using doubles. Have students discuss each fact and sort the flash cards based on strategy.
If you don’t know 9 + 3, how can knowing 10 + 2 help you?
If you don’t know 9 + 8, is there a doubles fact that can help you? How?
(use of strategies) If you don’t know the sum of 8 + 5 (or any other fact), what are some good strategies you can use to help you figure out the answer? (finger counting isn’t appropriate, looking for mental math ideas) Have students think, pair, share ideas. Write all ideas on board for class to see.
(making 10) Meghan wants to have 10 donuts in each box. How many more donuts does she need to put in each of the following boxes? A box with 9 donuts? A box with 8 donuts? A box with 3 donuts?
(doubling) Sherry already has 4 erasers. Now her goal is to collect 20 in all. She got 4 more on Monday and 8 on Tuesday. How many does she have in all? How many more does she need to make her goal?
(halving) Connie and Cheryl are twins. Connie’s hair is twice the length of Cheryl’s hair. Connie has decided that she wants to cut her hair to be the same length as her sister’s. Connie’s hairdresser measured her hair and it is 16 inches long. How long will the twins’ hair be?

SLIDE-BASED TASKS

These links are HCPSS created instructional tasks. These tasks are provided in Google slides. These tasks should be used for inspiration and resources, but instruction should start with students having the opportunity to engage with the math first (often involving physical and/or visual models) followed by discussion and explicit instruction to ensure student understanding.

Using 10 and Related Subtraction Facts (+/-)

Near Doubles (+/-)

Mixed Facts (all strategies taught)

Print Resources from Mastering the Basic Facts Addition and Subtraction PDFs via Google Links to an external site.

Additional Tasks

These links provide instructional ideas connected to this standard.

Hitting The Target Number Links to an external site. (Illustrative Math)

Tasks From Print Resources

These publications have been provided for each school. They are typically stored in team closets or the media center. Check with your team leader if you cannot find them.

Print Resources
Book Title	Grade	Pages
Teaching Student-Centered Mathematics	K-3	100 (One/Two-More- Than Dice, Activity 4.1) 100 (One/Two-More- Than Match, Activity 4.2) 100 (Lotto for +1/+2, Activity 4.3) 100 (What's Alike? Zero Facts, Activity 4.4) 101 (Double Images, Activity 4.5) 101 (Calculator Doubles, Activity 4.6) 102 (Double Dice Plus One, Activity 4.7) 103 (Make 10 on the Ten-Frame, Activity 4.5) 104 (If You Didn't Know, Activity 4.9) 106 (A Plus-Five Machine, Activity 4.10) 106 (Say the Ten Fact, Activity 4.11) 109 (Build Up Through the Ten-Frame, Activity 4.12) 109 (Back Down Through the Ten-Frame, Activity 4.13) 110 (Missing-Number Cards, Activity 4.14) 111 (Find a Plus Fact to Help, Activity 4.16)
Mastering The Basic Facts in Addition and Subtraction	K-2	Quarter 1: Review grade 1 facts: +/- 0, 1, 2; make ten; +/- 10; doubles Chapters 2, 3, 4, 5, and 6 Quarter 2: Make ten and some more (i.e. 8 + 5 = 13, 9 + 6 = 15) Chapter 7 Quarter 3: Near doubles (i.e. 5 + 6 = 11, 8 + 7 = 15) Chapter 8 Quarter 4: All facts
Nimble With Numbers	1-2	33-100
Groundworks: Reasoning about Number	2	64-72
Math Intervention: Building Number Power	PK-2	125 (Adding Doubles and Near Doubles) 131-136 (Fact Families)
Roads to Reasoning	2	40 (Double Desser)
Math In Practice Teaching Second-Grade Math	2	Module 2

Centers

These print resources can be used during independent or center time. These resources could also be used as lesson seeds.

INDEPENDENT PRACTICE/HOMEWORK/ASSESSMENT

These resource sheets can be used for independent practice, homework, or assessment. They are intended to reinforce procedures and concepts. They should not be used as a source of direct instruction or whole-group practice.

Review of 1st Grade Facts:

Make 10 and Some More (+/-):

Near Doubles (+/-):

Mixed Facts (all strategies taught):

Timed Assessments:

Full Standard

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

2OA2 Anecdotal Data Collection Tool (Addition) Links to an external site.

2OA2 Anecdotal Data Collection Tool (Subtraction) Links to an external site.

Rubric (for thinking and reasoning evidence)

Use this rubric for observation and constructed responses (tasks that require explanation, justification, and/or representation).

Rubric for Tasks Download Rubric for Tasks

(pdf)

For interviews:
Use the interview recording sheet Links to an external site.with a set of facts that students are working with in the classroom.

For observations:
Use the observation recording sheet Download observation recording sheet

with games and activities used in the classroom during independent practice or center time.

Visit the SBIR (Standards Based Instruction and Reporting) tab in Course Essentials for more information and clarification. There you will find the measurement topic crosswalk, report card comments, links to professional learning/resources and guidance.