Although I greatly enjoy reading about science, my reading rarely follows an organized plan. This approach may not be the most effective or efficient way to improve my mind, but at times it yields some nice surprises. Recently, I read an editorial by Gerard Piel (1986) in which he quoted James B. Conant as saying, Being well informed about science is not the same thing as understanding This quote from On Understanding Science (1947) struck me as pinpointing a basic problem in science education today: we are much more successful in presenting students with facts about science than in giving them what Conant calls a 'feel' for the Tactics and Strategy of Science. This quote led me to reread On Understanding Science, which I found much more interesting than when I first read it. Perhaps I am now more convinced of the need to lead our students to understanding, instead of just to information about science. Conant's argument was that, for the average person, the best approach to science is through the history of science, through studying case histories of scientific discoveries. This can be a less anxiety-producing approach since many people are more comfortable with history than with science. Also, little factual knowledge is needed to understand the early days of a science. Most importantly, as Conant said, the early days one sees in clearest light the necessary fumblings of even intellectual giants when they are also pioneers. In other words, an historical approach can give students insights into the tactics used and the problems encountered by scientists in their work. It brings students much closer to the feel for science that Conant saw as crucial to what we now call scientific literacy. Shortly after rereading Conant's book, I happened to pick up The Transforming Principle by Maclyn McCarty (1985). McCarty worked with Oswald Avery and Colin MacLeod in identifying DNA as the genetic material or what they called the transforming principle. McCarty's description of the discovery that genes are made of DNA provides an almost perfect case history with which to give students an understanding of science. The examples that Conant used involved 17ththrough 19th-century chemistry