Scale Factor Part 2

Scale Factor Part 2

Learning Target: I can find scale factor and missing lengths in word problems using equivalent ratios.

Conversions = special ratios used to convert between units of measurement

EXAMPLES:

12 inches = 1 foot

8 oz = 1 cup

12 eggs = 1 dozen

Math Conversions you need to know:

• 100 centimenters = 1 meter

• cent means 100, 100 pennies in 1 dollar

Math Conversions practice

• 100 centimeters = 1 meter

• How many centimeters are in 4 meters?

• How many centimeters are in 7 meters?

Multiple Choice

How many centimeters are in 4 meters?

• 4,000

• 40

• 400

• 14

Scale Factor Formula

• Sometimes we cannot easily find a missing multiplier

• We can use the scale factor formula if we know corresponding sides

• Notice the equivalent fractions

Multiple Choice

Find the scale factor from the big(new) to small shape (original). Remember to simplify your fractions

• 2/3

• 3/2

• 1/2

• 1/3

Scale Word Problems

• Two houses are drawn using the given scale 2 inches = 5 feet

• The house drawing is 8.5 inches tall.

• How tall is the house?

• Remember there are two ways to solve equivalent ratios

• Find the Missing Multiplier

• OR

• Cross multiply/Butterfly Method

Multiple Choice

A house is drawn 3.5 inches tall. The scale used to draw the house is 1 inch = 20 feet. How tall is the house in feet?

• 70 feet

• 5.7 feet

• 42 feet

• 16.5 feet

What's next ...

-IXL practice J.1-4

-IXL practice CHOOSE TWO F.2/F.3/X.15/X.17

-Scale Factor Video #1

-Scale Factor Video #2

These students need to stay online, you are missing your test:

Practice Test #2

-reviewing conversions

-scale factor

-scale drawing word problems

Conversions = special ratios used to convert between units of measurement

100 centimeters = 1 meter

How many centimeters are in 5 meters?

Multiple Choice

How many centimeters are in 2 meters?

• 2,000

• 20

• 200

• 12

Equivalent Ratios: Find the value of x

• FInd the scale factor for the denominators then use that to find x

• Use cross products to find the value of x

Multiple Choice

Find the value of the missing number.

• x=6

• x = 42

• x =7

• x =14

Find the scale factor?

• Use the scale factor formula: NEW/original

• The new shape is A the original shape is B

• Find corresponding side lengths and simplify the fraction

• 8/12 = 10/15 = 6/9 = 2/3

Multiple Choice

Find the scale factor from HGI (new) to KJI (original)

• 2/3

• 1/3

• 3/2

• 1/2

Multiple Choice

Bailey drew a truck that was 6 inches long. She used a scale 1 inch = 2 feet. How long is the truck in feet?

• 2 feet

• 12 feet

• 3 feet

• 6 feet

Alex is going to draw an eraser using the scale 1 inch = 2 centimeters. How long will this eraser be?

• How many centimeters is this eraser?

• Set up fractions: 1 inch/2cm ?/7 cm

• Solve for the missing number

Multiple Choice

Bree is drawing an extra large pencil. Her scale is 2cm = 1 foot. How many feet tall will her pencil be?

• 45 feet

• 9 feet

• 4.5 feet

• 9 cm

Time for Scale Copy Assessment #2