Strengths and weaknesses of evolution
Is "strengths and weaknesses" an appropriate strategy for teaching evolution at the secondary level? The answer requires understanding basics of science and scientific theories.
To begin with, scientific usage of "theory" differs from everyday usage. In common usage a theory is simply a conjecture. In science it's a well accepted formulation which makes logical connections among observations and evidence. The most useful theories make the most fruitful predictions. Since scientifc theories make useful predictions they may be incomplete, but not "wrong". They may be modified or replaced by better theories which explain more phenomena or explain phenomena more precisely.
Introducing a scientific theory by presenting its "strengths and weaknesses" suggests that it might be wrong and that scientists validate theories by looking at "both sides" in the same way as trial lawyers. This is seriously misleading. Scientists validate theories by experimentally testing their predictions and subjecting conclusions to peer review.
The "weaknesses" of a theory are properly viewed as limits to the range of phenomena that it can predict and the precision with which it can predict. "Weaknesses" do not imply that a theory is incorrect.
Newton's theory of gravity illustrates these principles. Newton's theory is still used in physics despite being supplanted by Einstein's relativity. Newton's theory works for everyday problems, but fails in systems that approach the speed of light. The "weaknesses" of gravity include that it doesn't work at extreme speeds and that it hasn't been tested at distant extremes of the universe. These "weaknesses" can only confuse the beginning student who has yet to understand Newton's theory.
Both Newton's theory and evolution are keys to understanding basic science. Students that reject theories because of "weaknesses" will remain scientifically illiterate.