These three variables are closely correlated. Good realization of these variables facilitates the inpidual to find the most effective learning strategy during the cognitive process.

Qu Lili says: “metacognitive knowledge, also refers to as metacognitive awareness, is considered to have important effects on cognitive activities like learning”(2016: 17).   

2.1.2 Metacognitive strategies

According to Brown et al. (1983), metacognitive strategies are higher executive skills that may entail planning for, monitoring, or evaluating the success of a learning activity. Learners manage, direct, regulate and guide their learning through metacognitive strategies (Wenden, 1998).

Although “Skills” are used to define “strategies”, there is difference between these two items. Afflerbach et al. point out the main difference between reading strategies and reading skills lies in the awareness. That is to say, reading strategies are “deliberate, goal-directed attempts to control and modify” the reading process but reading skills are “automatic actions with speed, efficiency, and fluency and occur without awareness or control involved” (Afflerbach et al., 2008: 368).

As one kind of learning strategies, metacognitive strategies are pided into four categories, according to O’Malley and Chamot(1990). They are selective attention, planning, monitoring, and evaluation. The following is the classification of metacognitive strategies in second language acquisition (SLA).