Virginia SOL 1.CE.1.e
The Standard
Solve addition and subtraction problems within 20 using various strategies (e.g., inverse relationships: if 9 + 3 = 12 then 12 - 3 = 9; decomposition using known sums/differences: 9 + 7 can be thought of as 9 decomposed into 2 and 7, then use doubles, 7 + 7 = 14; 14 + 2 = 16 or decompose the 7 into 1 and 6; make a ten: 1 + 9 = 10; 10 + 6 = 16).
Virginia Standards of Learning for Mathematics · The student will recall with automaticity addition and subtraction facts within 10 and represent, solve, and justify solutions to single-step problems, including those in context, using addition and subtraction with whole numbers within 20.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students find sums and differences within 20 without relying only on counting one by one. They use known facts, make ten, use doubles, or break apart numbers. They show why their answers work.
What Mastery Looks Like
- A student solves mixed addition and subtraction problems within 20 accurately. The student chooses an efficient strategy and uses drawings, equations, or words to explain the answer.
Common Misconceptions
- Students may count every object instead of using a known fact. They may reverse numbers when subtracting, or break apart a number without keeping its total the same.
How to Assess It
- Exit ticket: Solve 8 + 7 and 15 - 8. Draw or write how making ten, using a known fact, or using related facts helped.
Lesson moves
Ways to Teach It
Give pairs counters and ten-frames to solve 9 + 6 and 15 - 6, then record each move with an equation.
Prompt students to explain in writing how knowing 7 + 8 helps them solve 15 - 8, then compare explanations with a partner.
Play Fact Match with cards showing equations, answers, and related facts, with students collecting sets that belong together.
Set up a classroom store where students add item prices within 20 and find how many coins remain after each purchase.
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Printable 1.CE.1.e Worksheet
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Related Standards
- 2.CE.1.b
Apply strategies (e.g., the use of concrete and pictorial models, place value, properties of addition, the relationship between addition and subtraction) to det...
- 2.CE.1.a
Apply strategies (e.g., rounding to the nearest 10, compatible numbers, other number relationships) to estimate a solution for single-step addition or subtracti...
- 2.CE.1.d
Demonstrate fluency with addition and subtraction within 20 by applying reasoning strategies (e.g., doubles, near doubles, make-a-ten, compensations, inverse re...
- 1.CE.1.f
Represent, solve, and justify solutions to single-step addition and subtraction problems (join, separate, and part-part-whole) within 20, including those in con...
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