Proportions and Scale Factors

Designing with
What is proportionality?
How do you use a scale factor to create
What is a Proportion?
 An equation stating that two ratios
are equal.
What does proportional mean?
 Having the same or a constant ratio
 Are the four sides of these
quadrilaterals proportional?
Scale Factor
 When you compare
measurements of
proportional objects,
you get a ratio.
 This ratio is called
the scale factor.
How are scale factors used?
(sample student answers)
 Maps
 Models
 Drawings
 Movie miniatures
Are dolls and action figures
accurate models?
 Are their
proportional to real
 Are they
proportional to the
environment that
they live in?
How do reality and
imagination coexist?
Your Goal:
 Design a doll or action figure
 Create an environment in which that
character would live (dream house,
secret lair, vacation motor-home, etc.)
 Decide how tall your character would be
in real life and how tall its figurine would
be. Use these measurements to create a
scale factor.
Math Man and his Magical
Mathematical Mansion!
Scale Factor: 6 inches = 7 feet
Simplifies to: 1 inch = 1 1/6 feet

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