I was recently asked to explain eye tracking to 4th grade students and talk to them about its applications.
An eye tracker is a device that uses projection patterns and optical sensors to gather data about gaze direction or eye movements with very high accuracy. Most eye trackers are based on the fundamental principle of corneal-reflection tracking:
I did not have time to prepare an activity, and I showed them some videos and they asked me questions. They got it, but I don't believe this is the best introduction.
I was thinking something along the lines of Christopher Bishop's Royal Institution Christmas Lectures with volunteers and physical objects.
How would you explain it to 9-10 year olds?