Grade Level: 9-12
Concept: Use models and pen-and-paper methods to illustrate prime factorization
Estimated Duration: 50 minutes
Objectives
Students will be able to:
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model factors using tiles and grid paper
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differentiate between prime and composite factor trees
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illustrate prime factorization using factor trees
Materials
Chalkboard
Grid paper
Markers
Math journal or paper
Tiles or cut-out paper squares
*White board (Optional)
Differentiation Strategies
These strategies are used to meet the varied needs of all learners:
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Varying academic levels: uses mixed-ability groups allow students to learn from one another, small-l and whole-group participation
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Visual learners: incorporates drawings of rectangles and factor trees
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Auditory learners: pairs students to work together and discuss solutions
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Kinesthetic learners: engages students in modeling and drawing rectangles to represent factoring
Key Vocabulary
Composite
Factor
Prime
Prime factorization
Warm Up
Direct Instruction
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Using grid paper, ask students to draw the rectangle that they create with the tiles.
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Ask them to use the grid paper to draw rectangles with 24 squares, 15 squares, and 11 squares.
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Ask students to share the factors they found for each of these numbers.
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Define composite and prime on the white board, and ask students to copy down these definitions on paper or in their journals.
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Discuss the difference between the definitions of prime and composite in everyday language and in mathematical language.
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Call on students at random to pick a ping-pong ball or a piece of paper with a number out of a jar.
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Have students raise their hand to indicate whether they think the number is prime or composite.
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Use the white board or chalk board to illustrate how to factor the number to determine whether the number is composite or prime.
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Call on students at random to show on the white board whether the numbers such as 25, 27, and 29 are prime or composite.
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Define composite factor and prime factor on the white board, and ask students to copy down these definitions on paper or in their journals.
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Illustrate the prime factorization of 12 with tiles and using a factor tree.
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Explain to students that prime factors are usually listed from least to greatest.
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If appropriate, mention the use of exponents.
Practice
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Create mixed ability pairs and ask students to use tiles, graph paper, and factor trees to show the prime factorization of three or four numbers.
Assessment
Closure
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Ask students to come up with ways to check their answers. If they do not mention them, suggest
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creating an additional factor tree
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multiplying the prime factors