Montana Math MT.8.G.1
The Standard
Verify experimentally the properties of rotations, reflections, and translations and understand that these are rigid transformations, lines are taken to lines, line segments to line segments of the same length, angles are taken to angles of the same measure, and parallel lines are taken to parallel lines. This standard should incorporate cultural context relating to Montana Indigenous Peoples and local communities.
2026 Montana Mathematics Content Standards
Teacher's field guide
What This Standard Means
What Students Need to Do
- Students slide, flip, and turn figures, then compare each image with the starting figure. They measure segments and angles, and check that straight lines and parallel lines keep those properties.
What Mastery Looks Like
- A student can carry out each move and use a ruler and protractor to check matching lengths and angles. They can trace a line and a pair of parallel lines to show what stays the same.
Common Misconceptions
- Students may think turning a figure changes its angles because it looks tilted. Some confuse a flip with a turn. Others think parallel lines stop being parallel when they become slanted.
How to Assess It
- Exit ticket: Rotate a traced triangle and two parallel lines 90 degrees. Record one matching side length and angle measure, then explain whether the lines stayed straight and parallel.
Lesson moves
Ways to Teach It
Trace a triangle and two parallel lines onto acetate; slide, turn, and flip it, then compare lengths, angles, and parallelism.
Sketch two parallel lines after a quarter-turn; explain why they stay straight and parallel, using your tracing as evidence.
Give pairs six coordinate cards; have them match each figure to its slid, flipped, or turned image and check one side length.
Project a credited Blackfeet beadwork photo; students test whether two motifs match by sliding, turning, or flipping a tracing.
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Printable MT.8.G.1 Worksheet
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