Ashli
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mythagon.bsky.social
Ashli
@mythagon.bsky.social
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mythagon.bsky.social
Then for HS it has this:
Students also formalize the notion of a transformation as a function from the plane to itself. When the transformation is a rigid motion (a translation, rotation, or reflection) it is useful to represent it using transparencies because two copies of the plane are represented, one by the piece of paper and one by the transparency. These correspond to the domain and range of the transformation, and emphasize that the transformation acts on the entire plane, taking each point to another point. The fact that rigid motions preserve distance and angle is clearly represented because the transparency is not torn or distorted.
February 19, 2025 at 5:10 PM
mythagon.bsky.social
The CCSS progressions has this:
Initially, students view rigid motions as operations on figures (“transformations in the plane”). Later, students come to understand that it is not the figure that is translated, rotated, or reflected, it is the plane that is moved, carrying the figure along with it. Students start thinking, not of moving one figure onto another, but of moving the plane so that the first figure lands on the second (“transformations of the plane”) without moving the coordinate grid. This change in perspective is makes it possible to describe the effect of a given rigid motion on any point in the plane.
February 19, 2025 at 4:56 PM