Grade Level: 6-8
Concept: Multiplying positive and negative integers
Estimated Duration: 40 minutes
Objectives
Students will be able to:
Materials
Chalkboard
Markers
Worksheet with integer multiplication problems
*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 to allow students to learn from one another, uses small- and whole-group discussions to ensure all students participate
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Visual learners: incorporates visual representations of numerical expressions
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Auditory learners: engages students in finding rhymes, stories, and sayings to remind them of integer multiplication rules
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Kinesthetic learners: engages students in modeling integer multiplication, coming up to the front of the room to share their work
Key Vocabulary
Absolute value
Integer
Negative number
Positive number
Warm Up
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On the board, provide examples of word expressions that can be represented by integers, such as:
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The Dead Sea is 420 meters below sea-level.
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The average temperature last week was 7 degrees below zero.
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Sara works in an office 17 floors above Barbara’s office.
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Invite students to the board to show how they can use integers to represent the expressions.
Direct Instruction
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Write and define the terms integer, negative number, positive number, and absolute value on the board.
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Ask students to explain how they multiply positive integers.
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On a white board, or a chalk board, write an example such as positive three times negative five on the board.
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Have students think about what happens when a negative integer is multiplied by a positive integer. Use a model to guide students, such as:
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Stan dug a hole 3 feet below ground level. Jan dug a hole that was 3 times as deep.
- Have students draw Stan’s hole and represent Stan’s hole with an integer.
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Have students draw Jan’s hole and represent Jan’s hole with an integer.
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Explain that this example demonstrates that multiplying a negative integer by a positive integer results in a negative integer.
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Use another model to demonstrate multiplying a negative integer by a positive integer, such as:
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Jim walked down 15 steps.
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Then he walk three times as many steps in the opposite direction.
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Have the students illustrate Jim’s path.
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Explain that this example demonstrates that multiplying a negative integer by a negative integer results in a positive integer.
Practice
Assessment
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Invite pairs to share their word expressions with the class and their solutions.
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Invite students to create integer multiplication problems on the board for the class to solve.
Closure
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Create heterogeneous pairs so that non-English speakers are partnered with English speakers. Have the pairs represent the word expression with integers.
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Ask the pairs to create a rhyme, a story, an acronym, or a saying to remember that the product of a positive integer by a negative integer is a negative integer and that the product of two negative integers is a positive integer. For example, “the enemy of my enemy is my friend” might illustrate the latter.
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Have the pairs share their ideas with the class.