Steve
Penultimate Amazing
I respectfully disagree. Most 7 year olds would indeed grapple with the concept as a whole. Many could repeat certain facts, for sure, but the abstract nature would exclude a fair percentage from having an indepth appreciation of it.
There are a few fundamental concepts that could (and should) be taught at a young age. For example, diversity within a population is an important basic that kids do well with and helps understand evolution later.
Athon
There does not appear to be any clear indication of what would be taught to each of the various age groups. I have assumed that the introduction of evolution to the younger kids would be similar to what you described in your second paragraph. I don't think anyone in this thread has seriously suggested that 7 year-olds receive instruction in the "abstract nature" of evolution, or are capable of "having an in-depth appreciation of it".
As I said up-thread my 7yo daughter seems capable of grasping some basic facts about evolution in relation to her interest in dinosaurs, but I think I will wait a few more years before I suggest to her that she read Darwin.