How symmetrical are faces?

Some famous models and actors are known for having very symmetric faces. Others have pronounced imperfections that make them beautiful. But just how symmetric is symmetric? Can we use mathematics to compare the symmetry of faces? And how sensitive is our intuition for facial symmetry?

In this lesson, students deepen their understanding of line reflections and line symmetry by drawing on and inspecting a number of famous faces, and develop their own metric for facial symmetry.

- Reflect points over the line of symmetry on several faces
- Measure the differences between actual and perfectly symmetrical (reflected) facial features
- Normalize the measures of symmetry to compare photos of different sizes

- Rulers with mm markings