Course Guide - USAID Teacher Education Project

But if the orientation of the shapes is not aligned, as in the figure below, children mayfail to see which are the corresponding sides. In this picture, the two triangles areexactly the same (congruent), but the orientation is different.In this second set of similar triangles, both the orientation and the scale factor aredifferent. In testing for similarity, it is helpful for youngsters to rotate theirworksheets and notebooks or use thin paper for tracing one figure and placing it overthe other.(This is much like a younger child's not realizing that an equilateral triangle with itsbase on the horizontal is congruent to the same triangle with a vertex "down.")b) Youngsters (and pre-service teachers) may not understand that to create similarfigures a scale factor involves multiplication or division, not addition or subtraction.