How to Scale

Why is scaling important?

• Imagine if you had to draw a “full-size” map of the United States!– How much paper would it require?– How much time would it take?

• Scaling allows us to take large objects or long distances and “shrink” them to a smaller size

All Maps Include a Scale Bar

• Scales give you an equivalence factor– Ex: 1 inch = 200 miles– Ex: 1 centimeter = 3 meters

Okay, so how do I scale?

• Figure out what scale you want to use first.– For our notes we will use 1 cm = 5 m, but you will

get the chance to make up your own scale later

• Measure the actual (real) distance• Convert the real distance to a scaled distance

A Sample Problem

• In a local park, the swings are 15 meters away from the slide. If I draw a scaled map of the park, how far apart from the swings should I draw the slide?– Step 1: What’s the scale?• Let’s use 1 cm = 5m

– Step 2: What’s the real distance?• 15 meters between the swings and the slide

– Step 3: What’s the scaled distance?• We need to do a conversion

1 cm

5 m=

x cm

15 m

• Cross multiply

1 cm

5 m=

x cm

15 m

(1) (15) = (5) (x)

• Solve for “x”

(1) (15) = (5) (x) 5 5x = 3 cm

You should draw the slide 3 cm away from the swings on your map

Practice

• Main Street at Disneyland is 225 m long. Use the same scale (1 cm = 5 m) to determine how long you should draw Main Street on a map of Disneyland.

RoundRobin

• Begin with partner who has the shiniest shoes.• Explain to your partner the steps you followed

to solve the problem.• Thank your partner.• Switch