There is an old saying that "good teachers are born, not made." I disagree. Vast improvements in one's teaching performance can be added to one's DNA-given endowments. But it takes dedication, time, and help. And there is no lack of assistance available through articles, including those in this book, tutors, video cameras for self-appraisal, seminars, even courses in some colleges, and models of good teaching among one's former professors and current colleagues.

Another dictum is "How one speaks is as important as what one says." This may be true only if the information presented is accurate and wisely selected. Of course, know your subject, but present it clearly and with contagious enthusiasm. Many instructors could profit by speech therapy. Often we speak too softly, enunciate poorly, emit "ahs" and "uhs," and sprinkle our speech with that senseless and tiring phrase "you know."

There was once a newly appointed assistant professor who was assigned to lecture in Biology 1. He performed poorly. In the early days in Biology 1 the lectures were televised for an overflow audience and for later replay. Said assistant professor was asked to observe himself in action, in the hopes that his faults would be recognized and corrected. He refused. Before long his ineffective teaching contributed significantly to his dismissal.

Psychologists tell us that reinforcing auditory input with visual input enhances a learner's understanding and retention. Instructors in the physical and biological sciences are blessed with abundant visual teaching aids: experiments, demonstrations, diagrams, etc. But creative teachers in other disciplines can often devise visual stimuli. I remember my gifted instructor in beginning German who drew two sketches on the chalkboard. Each showed a room with a window and a table. On one figure he wrote prepositions taking the accusative case (gegen den Tisch ) and on the other the prepositions that require the dative case (bei dem Fenster ).

In the late 1960s, in response to student criticism of the lecture system, I brought theater into the classroom by impersonating some famous biologists, such as Darwin and Pasteur. Although this innovation is for the bold and courageous, all good teachers are actors, more or less. Vocal variation counteracts monotony; use of gestures, eye-to-eye contacts, and facial expressions impart zest; similes, metaphors, and personal experiences reinforce the text and increase student interest. Humor also helps.

There are many other factors that affect good teaching. Some professors appear to be insensitive to the physical conditions in lecture, seminar, and laboratory rooms. I have entered a general classroom, as students were leaving, to find it poorly illuminated and the air warm and fetid. Lights had not been turned on and windows not opened. No wonder the students became drowsy.

Finally, there are philosophical and educational ingredients of good teaching that are considered in other essays in the volume. I have discussed only a few practical aspects.