This question has entertained a significant number of my neurons for the past 20 years, and will doubtless continue to do so. Part of the problem is that it takes me a while to resolve difficult issues, part of the problem is that I am often guilty of lacking insight, and part of the problem is that the answers to that question are forever shifting.
Several years ago, my colleague and friend, Joel Hagen, approached me about writing a book with him and Douglas Allchin about using recent historical case studies as a mechanism for teaching students about how biology actually gets done. Since I knew nothing about the topic, I immediately said "yes", and thus became a part of the Doing Biology project. It's a wonderful little book that works at pretty much any level. Check it out!
Hagen, J., Allchin, D., Singer, F. 1996. Doing Biology. HarperCollins
College Pub. New York.
Since coming to Radford, I've been trying to make biology a more active learning process for the students. I find that I can speak until I'm blue in the face (which takes a very long time since I do like the sound of my own voice), but that the best learning occurs when students have to deal with real data. Thus I've worked (again with several wonderful colleagues) to develop numerous new labs, and also techniques for using statistical approaches for evaluating data that can be used by nonmajors at an introductory level. Some published (or hopefully soon-to-be published) references are:
Singer, F., Hagen, J., Sheehy, R. 2001. The comparative method, hypothesis testing and phylogenetic analysis: an introductory laboratory. American Biology Teacher 63: 518-523.
Kugler, R.C., Hagen, J.B., Singer, F. Teaching statistical thinking in introductory biology. Submitted to the Journal of College Science Teaching.
I'm always happy to discuss ideas about how to teach, so feel free to contact me about my latest state of confusion.