Materials
DE Marker
15 Small White Boards
Reminders
Use similar triangles to find the length of
side x:
6
7.5
10
x
150
Get out your agenda if you see
your name below. You need to
come to my room tomorrow.
Period 4
Period 5
Period 6
Stretching and Shrinking:
Scale and Scale Factor
How do I determine scale
and scale factor between
models and reality?
Questions:
What does scale
mean?
Notes:
Scale – the ratio of a length on a drawing or model to the
length of an actual object
Note: a Scale can have different units
Example:
Questions:
What does scale
factor mean?
Notes:
Scale Factor – gives how many TIMES larger or smaller an
object is
Note: a Scale Factor must have the same units and can be
written using a colon (ex. 1:23,000)
Example:
1:16,000,000
1:1,300,000
Questions:
How do I write
scale?
Notes:
Example:
A map shows 2 inches = 6 feet
Write this as a ratio:
2 𝑖𝑛𝑐ℎ𝑒𝑠
6 𝑓𝑒𝑒𝑡
1 𝑖𝑛𝑐ℎ
= 3 𝑓𝑒𝑒𝑡
Simplify so that the numerator has a length of one.
1
𝑐𝑚 = 2 𝑚𝑒𝑡𝑒𝑟𝑠
3
(3)1
𝑐𝑚 = (3)2 𝑚𝑒𝑡𝑒𝑟𝑠
3
1 𝑐𝑚 = 6 𝑚𝑒𝑡𝑒𝑟𝑠
Questions:
How do I
determine scale
factor?
Notes:
Make sure both amounts are using the SAME UNITS.
1 inch on a map = 10 feet in reality
Since there at 12 inches in a foot
1 inch = 10(12) inches
1 inch = 120 inches
1:120
The scale factor from the map to reality is 120.
THIS MEANS THAT IF WE MULTIPLY A MEASURMENT ON
THE MAP BY 120, WE WILL GET THE LENGTH IN THE REAL
WORLD.
Class Activity
1. Work on WS 5-8 Practice A with your table partner
2. We will work the problems together
3. Be prepared to share with the class
Class Activity
Class Activity
Class Activity
Class Activity
Class Activity
Class Activity
Class Activity
Class Activity
Class Activity
Homework
WS 5-8 Practice A and B
AND Cornell Notes
Summary