The frequent question:
Please, ftk, explain what the difference between micro- and macro-evolution is. How does one distinguish between microevolution and macroevolution in a particular evolving form?
This is an issue of empirical evidence in comparison to historical inference.
Empirical evidence is evidence that one can see, hear, touch, taste, or smell; it is evidence that is susceptible to one's senses. Empirical evidence is important because it is evidence that others besides yourself can experience, and it is repeatable, so empirical evidence can be checked by yourself and others after knowledge claims are made by an individual.
At issue is whether we have seen with our own eyes macroevolution or microevolution occuring in nature. Microevolution is frequently seen and involves only changes in size, shape, color, or minor genetic alterations. No one questions these types of evolutionary changes.
But, macroevolution, on the other hand, would have to provide evidence that the offspring of an animal or plant was able to evolve, for example, a different and improved set of vital organs that could be inherited. Despite many breeding experiments trying to cause such changes, this has never been observed. Micro changes are trivial in comparison to the long-sought macro changes.
All known species appear fully developed, not partially developed. They show design. There are no examples of half-developed feathers, eyes, skin, tubes (arteries, veins, intestines, etc.), or any of thousands of other vital organs. These type of changes have not been observed in nature.
So, what we rely upon are theories about these macroevolutionary changes that are rife with inference based speculation, extrapolation and no small amount of imagination in endless circumstances.
For evidence of "evolution", Darwin suppporters will reference empirical evidence for natural selection in moths, mice, or ice fish, and declare "evolution" as "fact", yet these changes we have witnessed with our own eyes are merely microevolutionary changes. They don't support Darwinism, which is the belief that everything we observe in nature today was the result of the first microbe that appeared from the 'primodial soup' (a theory which is fast falling by the wayside as well) to everything we observe in nature today by means of nothing other than the mechanisms of evolution...no source of intelligence required.
From those microevolutionary examples of natural selection, we are to consider various fossil series and extrapolate the evidence to the point where we are to accept as "fact" the following macroevolutionary examples in the textbooks:
-evolution of whales fossils
-evolution of horses
-evolution of humans
-evolution of amphibians, etc..
We have never observed these types of changes actually taking place, but rather rely on historical inference to support the conclusions.
The whale of a tail and other fossil examples that are said to support the above conclusions may actually be the result of macroevolutionary change, but then again, they may not.
As the Design inference spreads throughout the world, the general public is opening it's eyes to what Darwinism actually is and what is being taught as "fact" in our public schools.
Darwinism is no different that the theory of Intelligent Design in regard to the fact that both theories are based on historical inference. Our students should be allowed to consider both.
Added in edit: Here is a link to an excellent article by Jonathan Wells in regard to the definitions of Darwinism/evolution/macroevolution/microevolution.