A Florida FAST 4th grade math practice test workbook for teachers, with a pretest, skill practice for all 39 benchmarks, mixed review and 2 full-length practice tests. Answer key included, so test prep is ready to go.
This Prime Numbers Worksheet helps 4th graders identify prime and composite numbers by listing every factor and explaining their reasoning in a word problem. An answer key is included, so practice is fast to assign and easy to check.
A Smarter Balanced (CAASPP / SBAC) 4th grade math practice test workbook for teachers, with a pretest, skill practice for all 38 standards, mixed review and 2 full-length practice tests. Answer key included, so test prep is ready to go.
A NJSLA-A 4th grade math practice test workbook for teachers, with a pretest, skill practice for all 30 standards, mixed review and 2 full-length practice tests. Answer key included, so test prep is ready to go.
Using this 4.OA.4 Fourth Grade Common Core lesson students determine whether a given whole number in the range 1–100 is prime or composite.
This planet prime vs planet composite activity is a number-card sorting game for 4th and 5th grade, with a recording sheet and factor pair practice page. Answer key included for quick checking.
Numbers with just two factors
Fourth graders learn that every whole number from 1 to 100 can be sorted by its factors. A prime number has exactly two factors, 1 and itself, like 7 = 1 × 7. A composite number has more than two, like 12 = 1 × 12, 2 × 6, 3 × 4. Kids find all the factor pairs of a number, learn that 1 is neither prime nor composite, and notice that 2 is the only even prime. The click comes when kids realize they can test a number by trying to build it as a rectangle: primes only make one long row.
Factors are easier to see than to memorize. These moves help kids understand why a number is prime.
Kids sort number cards onto two planets after building each number with tiles. If the tiles only make one long row, the number lives on Planet Prime. Arrays make the idea concrete before kids use multiplication facts.
Why it works: going from real objects to pictures to symbols is a core recommendation of the U.S. Department of Education's elementary math guide.
Try it withPlanet Prime vs Planet Composite ActivityActivitiesOpen it →Play the prime numbers song at the start of math for a few days. Then hide the screen and see how many primes under 50 kids can list. A catchy tune helps with the list, and you can focus class time on the reasoning.
Why it works: a catchy, repeating tune gives the brain a hook to hang words on, so sung text is remembered better (Wallace, 1994).
Try it withPrime Numbers SongSongsOpen it →Model finding factor pairs in order: 1 × 24, 2 × 12, 3 × 8, 4 × 6, then stop when the factors meet. Showing the stopping point helps kids work faster and be sure they haven't missed one.
Why it works: handing over the work step by step, from teacher to student, is one of the most widely used teaching frameworks (Pearson and Gallagher, 1983).
Try it with4.OA.4 Fourth Grade Common Core LessonCommon Core LessonsOpen it →Fourth graders love a good number mystery. These keep factor practice fun.
WorksheetsFind the factor pairs for each number and decide if it's prime or composite.
Open Prime Numbers Worksheet →
WorkbooksTry test-style questions on factors and primes to build confidence for test day.
Open Florida FAST 4th Grade Math Practice Test Workbook →
Test PrepPartners roll two dice to make a number and race to say prime or composite. Prove it with factors!
Open Smarter Balanced (CAASPP / SBAC) 4th Grade Math Practice Test Workbook →Teacher favorites right now: Florida FAST 4th Grade Math Practice Test Workbook, Prime Numbers Worksheet and Prime Numbers Song.
A prime number is a whole number greater than 1 that has exactly two factors: 1 and itself. Examples are 2, 3, 5, 7, 11 and 13.
No. The number 1 has only one factor, itself, so it is neither prime nor composite. This is a common trick question!
There are 25 of them: 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89 and 97.
Use small objects like coins or cereal. Pick a number and try to arrange that many into equal rows. If the only rectangle is one long line, the number is prime.
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