Our students entering chemistry appear well prepared to deal with certainties in a scholarly fashion. If A = B and B = C then A = C. This type of neat solution seems to have preoccupied the students’ early years and then suddenly, there are significant figures. The rules for significant figures are not difficult. The concept is not difficult. But psychologically, our students appear unready to accept uncertainties. The very notion of significant figures is contrary to their vision of science and of education.
Some years ago we introduced a project which unintentionally contained an ambiguity. In order to simplify the mathematics, the atomic masses of the atoms were rounded to integers. Students came to an atom with a mass of 40 and could not distinguish whether the atom was Ca or Ar. At the time, we decided that we would correct this mistake for the next year’s assignment, but this year we were forced to respond with, “I guess it could be either one. How would you indicate that.” Well, this was a pretty long assignment, spanning about three weeks, and the “or” which crept into the results table kept slapping the students in their respective faces and refused to go away. Our students were unprepared and unable to function logically with that little “or” in there.
After a week of agony we realized that the situation would not be alleviated next year by correcting the assignment. It would just go back into hiding. So we responded by focusing on the teaching of ambiguities, the use of logical operators such as “or” and “xor”, and if-then statements, the uncertainty in measurement and the uncertainties in language. In fact, we later expanded the assignment to contain many different levels of uncertainty.
We also have one class devoted to a lecture/discussion concerning, if a tree falls in the forest …
The three pronged solution involves
1. the nature of sound and the need for a receiver such as an ear to convert silent sound waves into the perception of noise. [straight science]
2. the ambiguity of the word “tree” and the requirement that a certain type of nervous system is needed to extract the concept of a tree from the mass of interconnectedness out there. [crooked science]
3. the uncertainty that there ever was a forest based upon the “brains in vats paradox”. [very crooked science]
We even have one day in which our chemistry teachers compete, via their students, in a lab contest. Teachers are not allowed to advise their own students, but may help other teachers’ students. Since these teachers are hoping that other students will do poorly, there is a tendency to, … how shall I put it, … to lie. To protect these students, teachers are required by law to lie in everything they say. This does not prevent them from nesting information in “if-then” clauses with “or” and “and” or “xor” and “imp” statements. The effect is somewhat chaotic but our students get a pretty good dose of dealing with ambiguities throughout the year. This particular contest is an alloy of The Great Harvard-Princeton Titration Contest, the Army-Navy football game, with a dash of our own special brand of eccentricity thrown in.
We no longer protect our students from ambiguities but rather, we hope for more mistakes so that unintended ambiguities will creep in to ruin our neatest assignments.