If cognition is learning then metacognition is learning how to learn. Metacognitive strategies are the strategies we employ when we learn.

Metacognitive strategies are things like planning, checking, monitoring, select, revision, evaluation.

Metacognition can be thought of as an aspect of Higher Order Thinking (HOT). Note that evaluation is listed by Bloom as a higher order cognitive strategy.

One justification for teaching metacognitive skills rather than cognitive skills is the half life of knowledge, which Wikipedia defines "The half-life of knowledge is the amount of time that has to elapse before half of the knowledge in a particular area is superseded or shown to be untrue" and the expanding body of human knowledge

If technology results in a decreasing half life and an increasing body of knowledge, then equipping students to be life long learners may be more important than the learning of facts

Links
http://en.wikipedia.org/wiki/Metacognition

[edit] Reference

Machlup, F. (1962). Knowledge production and distribution in the United States. Princeton, NJ: Princeton University Press.



I think people learn their meta skills in areas which interest them deeply - it could be chess or cricket (shane warne has v good meta skills on the field and perhaps poor ones off the field). Also see improvementRavine and genius

the concept of declining half life of knowledge does give a strong justification for deemphasising instruction, except in the following contexts,
1 learning the building blocks for higher order thinking, general learning how to learn skills
2 "web2.0 skills" as we enter the realm where all or most of knowledge will be accessible through the internet
3 knowledge that is not learnt spontaneously, alan kay's list on non universal knowledge
4 vocational training for immediate use

The half-life of knowledge differs from the concept of half-life in Physics in that there is no guarantee that the truth of knowledge in a particular area of study is declining exponentially.
http://en.wikipedia.org/wiki/Half-life_of_knowledge

I would say that at any given time some knowledge is more durable and important than other knowledge - and that "half life of knowledge" arguments obscure that fact in a similar way that the "digital immigrants / digital natives" doesn't really help point a way forward. These terms are provocative and good discussion starters but not all that insightful in terms of helping "what to do"