The Socratic Method: Teaching [binary arithmetic] by asking instead of by telling by Rick Garlikov.
“The following is a transcript of a teaching experiment, using the Socratic method, with a regular third grade class in a suburban elementary school. I present my perspective and views on the session, and on the Socratic method as a teaching tool, following the transcript.”
This was only one of several excellent links I found at Ask MetaFilter: Numbers are fun!. The question was about “examples of number systems not based on western sets of 10. Anyone know of good info on non-standard number systems used in other cultures or for niche purposes, such as hexadecimal?”
Another fun web page is The Pi Code: “a base-26 system (the letters of the alphabet, with a=0) [is used] to write out Pi and then the string [is searched] for the appearances of English words.”