Five pages that build from pictures of factor pairs to prime factorization. Page 1 shows every rectangle that can be made from 12, 18, 20 and 24 squares, so students write each factor pair (3 rows of 6 is 3 × 6) and list the factors, then draw every rectangle for 10 and 16 on grid paper. Page 2 writes every factor pair of 30, 64, 84 and 144 in T-charts, tests whether a one-digit number is a factor (6 × 14 = 84, but 90 ÷ 7 leaves a remainder), and solves puzzles such as two factors of 48 that add up to 14. Page 3 writes ten multiples of two numbers, circles the ones they share and finds the least common multiple, circles the multiples of 9, 7 and 12, and fills in factor and multiple both ways: 7 is a factor of 63, and 63 is a multiple of 7. Page 4 draws rectangles to show that 7 and 11 are prime and 9 is composite, sorts sixteen numbers into prime, composite and neither, gives a factor pair to show why, and compares prime and composite numbers. Page 5 lists factors to find the greatest common factor of two and three numbers, makes factor trees for 24, 60 and 84, and solves a gift-bag story.
Give pairs of students 12 square tiles and ask them to build every rectangle they can. Record each one as a factor pair on the board, then ask why 5 × 2 is missing (5 is not a factor of 12). Repeat with 7 tiles: there is only one rectangle, which is what makes 7 prime. Before page 5, build a factor tree for 24 two ways (4 × 6 and 3 × 8) and show that both end with the same primes.
Ask your child to find every way to put 24 cookies or crackers in equal rows, then the same for 23. Point out numbers on house numbers, prices and clocks, and ask whether each one is prime or composite and how they know.
This pack supports the following Common Core State Standards for Mathematics:
© Copyright 2010. National Governors Association Center for Best Practices and Council of Chief State School Officers. All rights reserved.
A 5-page factors and multiples pack for 4th and 5th grade. Read factor pairs from rectangles of squares, draw every rectangle for a number on grid paper, and write every factor pair in T-charts for numbers up to 144. Test whether one number is a factor of another, list multiples, circle common multiples and find the least common multiple. Draw rectangles to tell prime from composite, sort numbers into prime, composite and neither, find the greatest common factor of two and three numbers, and make factor trees. Every page comes in color and in black and white. Answer keys included.
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