Montana Math MT.CORE.GEOM.TRANS.1

MathGrades 9–12Transformations

The Standard

Represent transformations in the plane using a variety of methods.

2026 Montana Mathematics Content Standards · Geometric Reasoning

Teacher's field guide

What Students Need to Do: Students show a translation, rotation, reflection, or dilation on a coordinate plane. They describe the same change with a drawing, point pairs, and a coordinate rule.
What Mastery Looks Like: A student draws the image of a triangle and labels its new vertex coordinates. Their rule works for every vertex, and their written description gives enough detail to repeat the move.
Common Misconceptions: Students may reflect across the y-axis by changing the y-coordinate instead of the x-coordinate. They may rotate around the wrong center or add to coordinates when a dilation requires multiplying.
How to Assess It: Give students a triangle with vertices (1, 1), (3, 1), and (1, 2). Ask them to reflect it across the y-axis, draw the image, list its vertices, and write the coordinate rule.

Lesson moves

Draw a triangle on tracing paper over a grid, rotate it 90 degrees counterclockwise about the origin, and record its new vertices.
Ask students why shifting (2, 1) three units left gives a different result from reflecting it across the y-axis.
Give pairs cards with coordinate rules, plotted triangles, and movement descriptions to match, then have them check every vertex.
Sketch a store logo on a grid, reflect it across a vertical line for a window decal, and label matching corners.

Free download

$Preview of the MT.CORE.GEOM.TRANS.1 printable worksheet$

A ready-to-print activity worksheet aligned to MT.CORE.GEOM.TRANS.1, with an answer key for the teacher on its own page. No account needed.

PDF, US Letter, prints cleanly in black and white.

Keep exploring

Grade, subject, topic, and the complete standard are prefilled. Create one free, no account needed.