Friday, August 10, 2007

Memorizing elements, or proteins or pathways ...

There has been an interesting discussions going on on the NSTA chemistry listserv on ways to encourage students to remember the names of the elements. This reminds me of experiences I have had in teaching introductory molecular and cellular biology at the college level.

In dealing with fundamental issues like energy transformation, cell replication, DNA replication and mRNA translation, it is easy to be seduced into presenting (and testing on) detailed lists of components or steps. I believe there may still be questions on Biology AP exams dealing with the order of compounds in tricitric acid cycle (as if that matters to anyone but a biochemist working on the reactions involved). Similarly, it is possible to spend time on the names of stages of mitosis or meiosis, while leaving the students in the dark about what, of significance, is happening. For example, how can a chromosomal rearrangement (that has no other effect on phenotype) lead to sterility or reproductive isolation? A person who can answer this question correctly really understands meiosis (and how it differs from mitosis).

The end result is that students tend to accumulate a vocabulary, which they and their instructors often mistake for understanding - yet, when placed in a novel situation, they are unable to use that information to think productively about the problem at hand. How many students are asked to learn the genetic code, yet cannot understand how a non-sense suppressor mutation works? And a point coming out of our own research, how many students understand that the genetic code is an algorithm for reading information stored in DNA, and not the information itself? This is a point of great interest from a evolutionary perspective.

Luckily (or unluckily) at the college level, there are few constraints on what I should or should not "cover" (something that I believe is not the case for K-12 teachers.) I have been free to change content at will, and together with a growing understanding of the value of formative assessment, begin to understand whether students are actually getting it.

The end result has been Biofundamentals, a course that replaces the standard major's introductory course and uses interactive engagement methods and virtual laboratories (like this one on working with bacteria). Over the years I have been teaching the course, I have removed more and more superfluous content largely because the inclusion of these topics demands a substantial commitment to presenting background materials necessary for the concepts to be usable by the student.

For example, a discussion of RNA interference or non-sense mutation suppression demands (I would argue) a more thorough understanding of the details of mRNA translation and roles of untranslated regions in RNA turnover than can be attained in the time available in an introductory course - yet now many instructors feel that they must keep their materials "up to the minute" by the inclusion of such topics? As an aside, this appears to be a particular problem in biology, since few introductory physics courses deal with relativity or quantum mechanics.

It must be constantly kept in mind that there are real constraints on effective learning. A curriculum must understand those constraints, otherwise it will inevitably sacrifice conceptual (working) understanding for trivial memorization.

This is of practical importance at the K-12 level, where instructors are being forced to address various unrealistic standards in the teaching of science. Even a cursory analysis suggests that the coverage specified by most state and national standards are extremely over-ambitious, and so actually antithetical to robust learning.

1 comment:

O.R. Pagan said...

You hit the nail on the head! Thanks!