stretching1studyguide

Make sure you can do the following by the assessment of investigation 1:

    • measure and identify types of angles
    • measure lines
    • compute area, perimeter, and circumference (if formulas are given)
    • convert percents to decimals
    • understand the term corresponding

Goals of the Investigation:

Students should understand that when enlarging or reducing figures:

    • the shape stays the same
    • the corresponding angles measure the same
    • the segments will either increase or decrease
    • the perimeter will either increase or decrease
    • the area increases or decreases (at a different rate)

OPTIONAL ANSWER KEY: parallelogram grows 140%

What do you notice about the shapes?

The shapes have stayed the same eventhough the image is 140% of the original.

What do you notice about the corresponding angles?

The corresponding angles all have the same measures eventhough the image is 140% of the original.

What happened to the lengths?

The lengths of the segments all grow 40% or are 140% of the original.

What has happened to the perimeter?

The image perimeter is 140% of the original or it is 40% larger than the original.

What has happened to the area?

The area also increases, but it is more than 40%. Area doesn't change at the same rate as the lengths or perimeter.

Dodd Middle School 2007-2008