A wonderful tool for teaching about random sampling and random assignment is available through the generosity of Scott Plous who created the invaluable online resource Social Psychology Network. I introduce students to Research Randomizer in my Psychology 205 “Statistics and Experimental Design” course where I require that they go through the excellent online tutorials. I often have students subsequently draw random samples from my class list who are the designated students-to-be-called-upon for the day. I see Research randomizer as a valuable teaching tool in almost any course where students and faculty are interested in an easy to use, valid, way of drawing random samples or to randomly assign participants to conditions. Much superior to drawing mixed numbers from my hat!
Here is a brief screencast one of my research assistants and i made illustrating how I introduce Research randomizer to my PSY 205 students.