~ 1.5 ~

Learning Targets

• I can describe the effect on a scaled copy when I use a scale factor that is greater than 1, less than 1, or equal to 1.
• I can explain how the scale factor that takes Figure A to its copy Figure B is related to the scale factor that takes Figure B to Figure A.

The size of the scale factor affects the size of the copy. When a figure is scaled by a scale factor greater than 1, the copy is larger than the original. When the scale factor is less than 1, the copy is smaller. When the scale factor is exactly 1, the copy is the same size as the original.

Triangle DEF is a larger scaled copy of triangle ABC, because the scale factor from ABC to DEF is (3/2). Triangle ABC is a smaller scaled copy of triangle DEF, because the scale factor from DEF to ABC is (2/3).

This means that triangles ABC and DEF are scaled copies of each other. It also shows that scaling can be reversed using reciprocal scale factors, such as (2/3) and (3/2).

In other words, if we scale Figure A using a scale factor of 4 to create Figure B, we can scale Figure B using the reciprocal scale factor, ¼, to create Figure A.

On each card, Figure A is the original and Figure B is a scaled copy.

1. Sort the cards based on their scale factors by listing the card number from least to greatest. *Hint* Card 4, 5, and 13 are all the least because their scale factor is 1/3.
2. Examine cards 10 and 13 more closely. What do you notice about the shapes and sizes of the figures? What do you notice about the scale factors?
3. Examine cards 8 and 12 more closely. What do you notice about the figures? What do you notice about the scale factors?