U1L10 Rigid Transformations

This lesson builds on prior knowledge about congruence to reinforce the idea that the rigid motions, translations, reflections, and rotations preserve distances and angles. These motions and the sequences of the motions, called rigid transformations, affect the entire plane, but students generally focus on a single figure and its image (the result of a transformation). Students also recall that the definition of congruent is any two figures where there is a sequence of translations, rotations, and reflections that takes the first figure onto the second. In this lesson, students study transformations on a grid, then in subsequent lessons in this unit, students learn precise definitions for rigid motions that apply off the grid. The study of coordinate geometry is reserved for a subsequent unit. Students work on an isometric grid to push them toward needing precise definitions. This activity includes lesson summary videos and practice problems.

By JOEL NELSON