NY Next Generation Math GEO-G.SRT.1

GEO-G.SRT.1 is a cluster heading. These are the individual standards under it.

• 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.b

  Verify experimentally that the dilation of a line segment is longer or shorter in the ratio given by the scale factor.

01

What Students Need to Do

Students test dilations with a specified center and scale factor. They verify what happens to lines through or away from the center and how segment lengths change.

02

What Mastery Looks Like

The student constructs image points along rays from the center and measures the correct scale ratio. The student explains the parallel-line and segment-length properties shown by the experiment.

03

Common Misconceptions

Students may dilate from the origin when another center is specified or add the scale factor to lengths. They may assume every image line is parallel to its original.

04

How to Assess It

Give a center, scale factor, one line, and one segment. Ask students to construct the images and verify both a line and length property.

1. 01

   Use rays, rulers, and tracing paper to dilate points from a marked center and measure ratios.

2. 02

   Ask why a line through the dilation center maps onto itself rather than a parallel line.

3. 03

   Play dilation check with centers, scale factors, diagrams, and claimed properties.

4. 04

   Analyze how a projected image changes size while rays originate at the projector lens.

• NY-8.G.1.b

  Verify experimentally angles are mapped to angles of the same measure.

• NY-8.G.1

  Verify experimentally the properties of rotations, reflections, and translations.