Grade 8
CCSS Math Standard: 8.G.1
Understand congruence and similarity using physical models, transparencies, or geometry software. Verify experimentally the properties of rotations, reflections, and translations: — a. Lines are taken to lines, and line segments to line segments of the same length. — b. Angles are taken to angles of the same measure. — c. Parallel lines are taken to parallel lines.
A lesson about lines, line segments, and rays that avoids dull memorization. Instead, we ponder this delightful question: Which is longer, a ray or a line? Then, kids consider what these different geometric concepts would think about each other.