NY Next Generation Math GEO-G.SRT.1.b
The Standard
Verify experimentally that the dilation of a line segment is longer or shorter in the ratio given by the scale factor.
New York State Next Generation Mathematics Learning Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students experimentally verify that dilation multiplies every segment length by the scale factor. They compare original and image lengths for enlargements and reductions.
What Mastery Looks Like
- The student constructs a dilated segment and computes the image-to-original length ratio. The ratio equals the specified scale factor across several orientations.
Common Misconceptions
- Students may add the scale factor to a length or reverse the ratio. They may think orientation changes the length relationship.
How to Assess It
- Give a segment, center, and scale factor less than one. Ask students to construct the image, measure both lengths, and verify the ratio.
Lesson moves
Ways to Teach It
Dilate several paper segments from one center, then measure and tabulate image-to-original ratios.
Ask why segment orientation does not change the image-to-original length ratio.
Play scale-factor match with original lengths, image lengths, and enlargement or reduction cards.
Check scale drawings by comparing corresponding lengths to the stated scale factor.
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Printable GEO-G.SRT.1.b Worksheet
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Related Standards
- NY-8.G.1.c
Verify experimentally parallel lines are mapped to parallel lines.
- NY-8.G.1.a
Verify experimentally lines are mapped to lines, and line segments to line segments of the same length.
- GEO-G.SRT.1.a
Verify experimentally that dilation takes a line not passing through the center of the dilation to a parallel line, and leaves a line passing through the center...
- GEO-G.SRT.1
Verify experimentally the properties of dilations given by a center and a scale factor.
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