5.4.A
The Standard
identify prime and composite numbers
Texas Essential Knowledge and Skills for Mathematics
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students decide how a whole number greater than 1 should be classified by finding its factors. They use factor pairs, arrays, or divisibility rules to support the decision.
What Mastery Looks Like
- Students correctly classify whole numbers greater than 1 and justify each choice with factor pairs. They explain that 1 belongs to neither group.
Common Misconceptions
- Students often label 1 as prime because it has only one factor. They may also think every odd number is prime or confuse factors with multiples.
How to Assess It
- Give an exit ticket: “Classify 1, 29, and 35. Justify each answer by listing all factor pairs.”
Lesson moves
Ways to Teach It
Give students 24 counters and have them build every possible rectangular array, then repeat with 23 counters and compare the results.
Ask students to respond: “Is every odd number prime?” Require a counterexample and a factor-based explanation.
Play a card sort where partners place number cards into prime, composite, or neither groups and check each choice with factor pairs.
Compare seating plans for 17 and 18 chairs by drawing equal-row arrangements and explaining why the available layouts differ.
Keep exploring
Related Standards
- 3.2.A
compose and decompose numbers up to 100,000 as a sum of so many ten thousands, so many thousands, so many hundreds, so many tens, and so many ones using objects...
- 2.7.A
determine whether a number up to 40 is even or odd using pairings of objects to represent the number
- K.2.I
compose and decompose numbers up to 10 with objects and pictures
- 6.7.A
generate equivalent numerical expressions using order of operations, including whole number exponents and prime factorization
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