Line up the people in order of height. Then find the median, Q1 and Q3. For some reason they all look very cranky...
http://www.subtangent.com/maths/median-and-quartiles.php

The Stroop Test is a fun and engaging way to collect numerical data for later analysis and display. From the flipchart: "In the Stroop Test, the participants are given a list of words, and are asked to say the colour of the word, and not the word itself ... Most people take longer to say the colour of the word when the colour of the word doesn't match the word itself."