If you want hands on learning, look no further. This is a hands on simulation that helps students understand how race is truly a human construction that has changed over time, rather than fixed, biological categories.
All you will need is this worksheet explaining the directions and access to colored markers/ pencils. Each student should have access to an array of marker colors. Their job is to categorize the marker colors, first in two categories, then four, then finally six.
This activity builds collaboration as students compare their own classifications with a partner and discuss. The take-away is that students understand how we have understood "race" over time has really been a series of arbitrary classifications constructed by humans.