Creationists like to frame evolution as a controversial theory distinct from the other well established theories within science, and they argue that simple honesty demands that the theory's weaknesses be included in any curriculum. But evolution is as well established as almost any other theory within science, having gone through a lengthy period of observation, experimentation, analysis, replication and argument and thereby passing the threshold for acceptance for the vast majority of scientists, as all theories must do if they are to become part of mainstream science.
The controversy that creationists point to is not a controversy within science, but one between science and and a particular set of religious beliefs. The weaknesses that creationists point to all fit into one of two categories: either they're not scientific weaknesses, or they're questions for which we have no answers as yet. Naturally non-scientific weaknesses do not belong in science class, and all theories have unanswered questions which can be included or not in a program as appropriate. For example, though we have far more questions than answers about dark matter and dark energy, any science class that happened to include a week on cosmology would probably want to mention them because they're fascinating topics likely to fuel students curiosity. But they're unanswered questions, not weaknesses.
So in the same way, it would be appropriate during a week spent on evolution to mention some topics with more questions than answers, such as the origin of flight or even the origin of life itself, because these are legitimate scientific topics within science about which many technical papers have been written.
What would not be appropriate would be to mention the irreducible complexity of hemoglobin or the unreliability of radiometric dating, because these are not scientific issues, indeed have such an insufficient scientific basis that no technical literature about them exists.
--Percy
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