Proportions

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Proportions

• Math Grades 6-8

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Teacher Page

• Content Math
• Grade Level 6-8
• Creator Abby Neiburger
• Curriculum Obj IV.M. The learner solves
  problems using ratios and proportions involving
  pricing, recipe conversion, medication dosage,
  and relative distance between locations. (G 1.6,
  1.10, 2.1, 2.2, 4.1 MA-1, MA-5 CF I.4.b.V.2.c
  LS 5,6,7)

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What is a proportion?

• A proportion is just two or more ratios that are
  equal to each other!
• You can check to see if ratios are equal by
  finding their cross products. That means just
  cross multiply!

• Proportion?
• 4
• 16
• Work it out!
• Yes! 16 16

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Your Turn!
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Blueprints!

• Blueprints for a house show a room that is 2 5/12
  inches long. The key to the blueprints says that
  ¼ inch on the blueprints represents 18 inches in
  the house. How long is the actual room?

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Lets set it up

• ¼ inch 18 inches
• 25/12 inches x inches
• ¼ x 25/12 18
• ¼ x 43½
• 4 ¼x 4 43½
• x 174
• The room is 174 inches or 14½ feet long.

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A MAP question

• The ratio of a persons weight on Earth to the
  persons weight on Mars is 2 to 0.76. If Dennis
  weighs 122 pounds on Earth, how much would he
  weigh on Mars? Be sure to provide the work that
  shows how you arrived at your answer.

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The scoring guide

• Exemplary Response
• 46.36 (pounds) AND 2 122
• 0.76 x
• 122 0.76 2x
• 92.72 2x
• 92.72 2 x
• 46.36 x
• OR Other valid process
• Score Points
• 2 points Exemplary response
• 1 point Correct process error in computation
• OR Correct answer only
• 0 points Other

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Another MAP question

• Your class has decided to crush the cans to save
  space. A full-size can is 5 inches tall, while a
  crushed can is 1 inch tall. If 175 full-size cans
  will fit into a garbage bag, about how many
  crushed cans will fit into the same bag? Be sure
  to provide the work that shows how you arrived at
  your answer.

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Scoring Guide

• Exemplary Response
• 875 AND 175x5 OR Other valid process
• Score Points
• 2 points Exemplary Response
• 1 point Correct process error in computation OR
  Correct answer
• 0 points Other