Overview:  The teacher launches the lesson with a review of some transformations.  The teacher asks students to name transformations, and students give the ideas of translations and glide reflections.  The teacher illustrates the translation using the letter “E” and uses the example of footprints in the sand to illustrate glide reflections.  Then a student names reflections, and the teacher reviews the vocabulary of “pre-image” and “image”.  The teacher asks students for examples of things that have reflective symmetry.  Students provide examples such as “the letter A” and “butterflies”.  The teacher tells students they’ll be working on a problem about reflective symmetry.

Prior knowledge:  The teacher attempts to connect with students’ prior knowledge of school mathematics.  Specifically, the teacher reviews different examples of transformations, including reflections.  When the students bring up reflections, the teacher asks students to consider things from their prior experiences that have reflective symmetry.  Students bring up examples that are not inherently mathematical examples, including a poster of a mountain reflected in a lake, the letter “A”, and butterflies.

Other points of interest:  The teacher elicits students’ prior knowledge by asking them to consider the transformations they remember.  It seems that the teacher in this launch does not have a pre-determined list of points to review.  Instead, the teacher allows students to suggest transformations they think of.  The teacher continues this activity until a student suggests reflections, and then the teacher gives a more thorough review of reflections.  The teacher does not review all the transformations; for example the teacher does not review rotations.  It seems the teacher may want to give space for students to suggest ideas, but the teacher is specifically interested in reflections, which constitute a fundamental aspect of the pottery problem.