Addition & Subtraction Through 20 Fact Fluency

Developing Fact Fluency

Addition & Subtraction Through 20

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.

 

Learning Targets (I can)

  • Recall facts that add and subtract within 20.
  • Use mental strategies to recall a fact when a fact can't be recalled quickly.

 

About the Math

  • 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.

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.

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.

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.

 

 

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