I teach a large lecture class every semester, and this past fall I taught or supervised three of them. So I'm always looking for ways to innovate. One of the best approaches in the classroom is to take advantage of the large size of a lecture class to bring experiences that would be impossible in a small class.
Today I ran across an article published a few years ago by Stephen Wolfman
The students' third assignment (of five) was to write a program that would accept a series of words and, for each word, calculate its value in the base 36 number system. Then, the program would report to the user whether the result was prime or composite. We encouraged students to share examples of prime words which they discovered, and the students responded by posting examples to the class newsgroup. Initially, these were mostly amusing English words, but soon a Finnish student chimed in with a handful of Finnish (and French, Spanish, and German) primes. A Vietnamese student contributed a list of Vietnamese words which (when spelled without their accents) were prime in base 36.
In this assignment, the diversity of student background contributed to the excitement of the assignment. Indeed, while I had hoped that different students would find quite different sets of words, I never imagined that they would search in other languages!
He discusses many other examples, including some ideas about how to use the psychology of crowds to bring students toward greater participation on the first day of class.