Math Misconceptions and Considerations HSG-SRT.A.1
Look closely at errors in students’ work (formative assessment) to help you reflect and make instructional decisions to suit all students’ needs.
I know where the center of dilation is…it’s in the center Relying on their knowledge of everyday vocabulary, students may misinterpret the location of the center of dilation. Misconception: Focusing on the word “center”, students tend to think that the center of dilation must be in the center of the pre-image.
What to do: Provide students with examples of dilations in which the center of dilation lies inside the figure, on the figure and outside the figure. Moving away from dilations on the coordinate plane may decrease their tendencies to misinterpret the center of dilation. Dilations without the coordinate plane will force student to rely on the properties of dilations instead of the properties of the coordinate plane.
Congruence and similarity are not related to each other Students may view congruence and similarity as two distinct and unique categories that do not overlap. Misconception: When students encounter a dilation under a scale factor of 1 or -1they do not recognize that the figures are congruent while also being similar. What to do: Providing students with examples where they are given a pre-image and image and ask them to work backwards to find the scale factor will allow them to discover that a dilation with a scale factor of 1 or -1 yields congruent figures. Also, having a discussion with students about figures that are congruent, similar, congruent and similar, or neither would be effective.