One of the oldest formal teaching techniques is from Socrates, where he taught others by answering questions with more questions. This 'Socratic questioning' is one of my personal favorites techniques simply because it works. Students tend to be very responsive because it is a naturally engaging and active type of learning, and it keeps a student's interest because it typically starts with that student's original question, so he/she already has some level of interest or curiosity because it has already sparked a question.
To demonstrate how this works, check the transcript from Rick Garlikov. He did an experiment where he wanted to teach a 3rd grade class how to do binary arithmetic, but he could only answer questions with more questions. It is a very well-done lesson, and I can understand his excitement when students began to master the arithmetic because I have been in this situation before...it is what teachers dream about every day when something 'clicks' with students.