2.4.A
The Standard
recall basic facts to add and subtract within 20 with automaticity
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students recall sums and differences through 20 without counting each amount. They recognize related addition and subtraction facts and give answers with increasing speed.
What Mastery Looks Like
- Students answer mixed addition and subtraction facts quickly and accurately without counters or fingers. They use known facts and related fact families when recall is not immediate.
Common Misconceptions
- Students may count every fact on fingers instead of recalling it. They may confuse addition and subtraction signs, reverse subtraction facts, or miss related fact families.
How to Assess It
- Give an exit ticket with 12 mixed addition and subtraction facts through 20. Allow two minutes and note accuracy and which facts require counting.
Lesson moves
Ways to Teach It
Have students build fact families with two-color counters, then hide the counters and state all four related equations.
Ask students to explain in writing how knowing 8 + 7 helps them solve 15 − 8.
Play Fact Match with cards showing equations and answer cards, with students pairing each equation to its total or difference.
Give a snack shop menu with prices under $20 and ask students to find totals and change mentally.
Keep exploring
Related Standards
- 1.3.D
apply basic fact strategies to add and subtract within 20, including making 10 and decomposing a number leading to a 10
- K.2.A
count forward and backward to at least 20 with and without objects
- 3.4.F
recall facts to multiply up to 10 by 10 with automaticity and recall the corresponding division facts
- 1.3.F
generate and solve problem situations when given a number sentence involving addition or subtraction of numbers within 20
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