One of my favorite exercises for intro stats. Students attempt to take a representative sample of words and estimate the mean word length in a passage of text. I've done this for 10 years now, and the result is similar every year. Students tend to oversample big words! [Thanks to the Lock family, authors of Unlocking the Power of Data textbook, for the idea - I just modified the passage to fit my audience,]

Can students pick a representative sample of words from a passage of Darwin's Origin of Species? Not quite...every year, they exhibit a tendency to oversample large words.

Demonstration of concepts covered in Biometry Class 9/26/2019

Comparison of a public opinion poll to a non-random sample of Fisheries, Wildlife, and Conservation Biology students

I polled students in my class about the debate, who they were likely to vote fore (before and after), etc. A key mistake, however, was that I neglected to allow for a third party candidate. A key teaching moment - thanks to one of my students - always create and test your surveys ahead of time (rather than creating them the morning of :)