Seminal work in the area of measuring both explicit and implicit knowledge in L2 learning has been carried out by Rod Ellis and colleagues (R. Ellis, 2004; R. Ellis et al., 2009). It is argued that explicit and implicit knowledge can be distinguished according to a number of criteria (see Chapter 4), that is, awareness or the absence thereof (conscious vs. intuitive), type of knowledge (declarative vs. procedural), accessibility of knowledge (controlled vs. automatic processing), use of knowledge, with implicit knowledge being used during fluent performance and explicit knowledge to resolve difficulties, systematicity and certainty of knowledge, availability or otherwise for self-report, and learnability, with explicit knowledge being potentially learnable at any age given sufficient cognitive maturity and implicit knowledge being subject to maturational constraints (R. Ellis, 2005). Accordingly, if explicit knowledge is to be operationalised in line with these criteria, a test measuring explicit knowledge would have a primary focus on form, the use of metalanguage would be encouraged, it would require or at least encourage learners to respond in line with known pedagogical grammar rules, and it would not impose any time pressure.