Virginia SOL 8.MG.3.a
The Standard
Given a preimage in the coordinate plane, identify the coordinates of the image of a polygon that has been translated vertically, horizontally, or a combination of both.
Virginia Standards of Learning for Mathematics · The student will apply translations and reflections to polygons in the coordinate plane.
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students find the new coordinates of each polygon vertex after a horizontal, vertical, or combined shift. They add or subtract the stated movement from the correct coordinate.
What Mastery Looks Like
- Students correctly update every vertex using the same coordinate rule. They can graph the image and check that side lengths and orientation remain unchanged.
Common Misconceptions
- Students may change the y-coordinate for horizontal movement or the x-coordinate for vertical movement. They may use the wrong sign, move only one vertex, or switch the coordinates in an ordered pair.
How to Assess It
- Exit ticket: Translate triangle A(-3, 1), B(2, 1), C(0, 4) five units right and two units down. List the new coordinates and write the coordinate rule.
Lesson moves
Ways to Teach It
Place a cutout polygon on a coordinate grid, slide it as directed, then record the new coordinates for every vertex.
Ask students to explain why moving four units left changes x but does not change y.
Play translation match-up with cards showing polygons, movement directions, coordinate rules, and image coordinates.
Use a city grid map to move a delivery marker between locations and write the resulting coordinate changes.
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Printable 8.MG.3.a Worksheet
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Related Standards
- 8.MG.3.d
Sketch the image of a polygon that has been translated vertically, horizontally, or a combination of both.
- 8.MG.3.b
Given a preimage in the coordinate plane, identify the coordinates of the image of a polygon that has been reflected over the x- or y-axis
- 7.MG.4.a
Given a preimage in the coordinate plane, identify the coordinates of the image of a polygon that has been dilated. Scale factors are limited to 1 4 , 1 2 , 2, ...
- 8.MG.3.c
Given a preimage in the coordinate plane, identify the coordinates of the image of a polygon that has been translated and reflected over the x- or y-axis or ref...
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