5.3.K
The Standard
add and subtract positive rational numbers fluently
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students add and subtract fractions, mixed numbers, and decimals accurately. They use common denominators, regroup when needed, align decimal points, and simplify answers.
What Mastery Looks Like
- Students choose efficient methods, find common denominators when needed, and align decimals correctly. Their answers are accurate, simplified, and reasonable based on an estimate.
Common Misconceptions
- Students may add denominators, line up decimal digits instead of decimal points, or ignore regrouping. They may also mishandle mixed numbers when subtraction requires renaming a whole.
How to Assess It
- Give an exit ticket with 3/4 + 2/3, 4 1/5 − 2 3/4, and 6.08 − 2.9. Ask students to show one key step for each.
Lesson moves
Ways to Teach It
Use fraction strips and decimal grids to model four problems, then connect each model to a written calculation.
Ask students to explain why adding denominators does not work when adding 2/3 and 1/4.
Play a partner card game where students draw two fractions or decimals, choose addition or subtraction, and check each other's work.
Plan a class party budget by adding item costs and subtracting the total from a fixed amount.
Keep exploring
Related Standards
- 7.3.A
add, subtract, multiply, and divide rational numbers fluently
- 6.3.D
add, subtract, multiply, and divide integers fluently
- 6.3.E
multiply and divide positive rational numbers fluently
- 7.3.B
apply and extend previous understandings of operations to solve problems using addition, subtraction, multiplication, and division of rational numbers
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