The definition that I use for metacognition comes from who states that:
Metacognition is needed to make human beings human. It is a reflection on their own thinking. It helps monitor understanding; predict performance; decide what is needed to be done next; check consistency between ideas and concepts; draw analogies that help advance understanding and learning. (30)
In an education situation, it is when students think about their own thinking and learning. This does not come naturally; it must be taught explicitly to them. There must be a safe environment where students feel safe to take risks and supportive activities that cause the students to reflect on what they have learned, or did not learn, and where and how they will need to take their next steps in their learning.