Despite common practice in a lot countries and Language Curricula, Second Language Acquisition is fundamentally different than Primary Language Acquisition. In Second Language Acquisition the Learner references the new language (in different ways depending on age) to the first language. Furthermore Children education on Second Language is different to Adult education. In general Children-learner tend to process second (or third) languages in ‘parallel’ (creating an own pattern) while adults tend to process second (or third) languages ‘sequential’ (associated to the patter of the Primary Language). (The detailed differences are not subject to detailed illustration in this article.)
To significantly improve the Learner’s progress of Adults requires a) leveraging on existing “Language learning experience” and b) tapping into Language Learning methods of Primary Language Acquisition. It remains very difficult to extrapolate generic models due to different learning type personalities but the Dogme & Direct model are interesting methods to consider for learners (and instructors).