According to Ellis (2004), in a practical definition, explicit knowledge deals with
language and the uses to which language can be put. This knowledge facilitates the
intake and development of implicit language, and it is useful to monitor language
output. Explicit knowledge is generally accessible through controlled processing. In
short, it is conscious knowledge of grammatical rules learned through formal
classroom instruction. In this respect, a person with explicit knowledge knows about
language and the ability to articulate those facts in some way (Brown, 2000). For
instance, Achmad knows every rule about present tense, but he frequently makes
mistakes in speaking and writing. However, such knowledge is easy for him while
having time to think of the rule and apply it (that is, in the context of a grammar
exercise or a writing assignment). Thus, on the basis of Achmad’s case, explicit
knowledge is learnable; for example, when grammatical items are given to learners,
they learn the items first in a controlled learning process. Explicit knowledge is also
obtained through the practice of error correction, which is thought to help learners
come to the correct mental representation of a rule. This works if there is enough time
to operate it; the speaker is concerned with the correctness of her/his speech/written
production; and s/he knows the correct rules (Krashen, 1987).