Reading through the student worksheet will give you an idea of how this lesson works as I have not typed up a lesson plan for this activity yet.
This lesson can be a lot of fun during the Halloween season and it is also a great way to hit several Math and Science standards at one time. Incorporate writing standards into this lesson by having students write a descriptive paper about their finished shrunken head. Then read the papers out loud to the class. See if the students can pick out which shrunken head belongs with each paper.