- This topic has 1 reply, 2 voices, and was last updated 11 years, 9 months ago by
.
-
Posts
-
8.G.3 Describe the effect of dilations, translations, rotations, and reflections on two-dimensional figures using coordinates.
Is it safe to assume that this refers to dilations through the origin, rotations centered at the origin by n*pi/2 (n an integer), and reflections over the axes or y=x, y=-x?
Or should we really prepare students as broadly as the standard says?
I only break this into so many cases because it says “using coordinates” and while students could “describe” what happens in the more general cases than the ones I described, they do not have the tools to “describe…using coordinates” that generally.
The standard is limited by what else students know at this grade level. This includes the cases you mention, and it might make sense for a curricular implementation of the standards to leave it at that. But there are other transformations that are possible, it seems to me. You could rotate by a multiple of $\pi/2$ around any point on the coordinate grid, for example.
- You must be logged in to reply to this topic.