Every year I have my kids draw a picture of their face. We looked at each others' faces to notice the parts and listed what we found: cheeks, eyebrows, chin, neck, nose, mouth, hair, eyes, and ears. Then we added smaller blocks as we noticed parts of those parts; lips and teeth in the mouth for example. Their list became quite extensive.
Students headed off with paper and mirrors. They looked at themselves and drew what they saw. If you look closely at the picture below you can see eyebrows, nostrils, and the bridge of his nose.
Six year olds never cease to amaze me (something I assume I share with most first grade teachers).