Introduction to Scale Factor and Scale Drawing

Scale Drawings

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Scale Factor

Introduction

• What do you notice about the drawing of the horse compared to the actual horse?

• What questions do you have about the two versions?

Now you try, did this potion make a person grow or shrink? Answer on the next slide.

Multiple Choice

What change was made to the actual horse?

• Exact Copy

• Reduction

• Enlargement

Poll

So did the potion make the person grow or shrink?

• Grow

• Shrink

Scale drawing

In order for an original drawing to be reduced or enlarged, every corresponding side must be PROPORTIONAL to the original measurements.

We use MULTIPLICATION to make things bigger or smaller.

Now you try, did this potion make a person grow or shrink? Answer on the next slide.

Multiple Select

Which pairs of corresponding sides are proportional?

• The bottom of each shape because 4 times 3 is 12

• The right side of each shape because 4 times 3 is 12

• The left side of each shape because 4 times 3 is 12

• The slanted line on the left because 2.2 times 3 is 6.6.

• The slanted line on the right because 2.2 times 3 is 6.6

Poll

So did the potion make the person grow or shrink?

• Grow

• Shrink

Multiple Choice

How is Figure F reduced to Figure B?

• Multiply each side by 1/2

• Multiply each side by 1/3

• Multiply each side by 1/4

• Multiply each side by 1/5

Fill in the Blank

The scale factor is ______ to enlarge triangle ABC to triangle DEF?

Using Scale Factors:

Multiple Choice

Which copies are scale drawings when compared to the original triangle?

• 1, 2, and 3

• 1 and 2

• 2 and 3

• 1

• 2

Multiple Choice

You try to find the new dimensions of the box. Click the picture to zoom.

• 2.8 in. by 6.3 in

• 30 in. by 66 in.

• 35 in. by 77 in.

• 3.5 in. by 7.7 in.

Open Ended

Explain why Copy 3 is NOT a scale drawing of the original triangle.

Multiple Choice

You try to find the new dimensions of the box. Click the picture to zoom.

• 40 by 50 in

• 4 by 5 in

• 14.4 in by 18 in

• 1.4 in by 1.8 in

Open Ended

Is Figure B an enlargement of Figure A? Explain why or why not.

Finding Scale factors

Multiple Choice

You try now. What is the scale factor of the rectangles in the image

• 3/2

• 2/3

• 1

• 3/4

The End

(or is it...?)

No, no it's not.