# Musical Math

```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
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Homework
WS 5-8 Practice A and B
AND Cornell Notes
Summary
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