Out-of-class vs. classroom-based learning: which is the best way to master a foreign language?

Mastering a foreign language entails becoming acquainted and gradually possessing features of a linguistic code which is different than one's mother tongue. Over the years various teaching approaches and educational theories have been implemented each boasting a new trend, each suggesting a new learning path. What has recently attracted scientific interest is the actual location where foreign language learning occurs. Where the learner is, i.e. inside or outside of a classroom is interconnected with the approach employed to master the target language. Typically, any kind of learning is associated with a classroom, a teacher, peers, and a formal curriculum. However, a classroom is not the only place where learning may occur. Out-of-class learning has always been happening but required an effort (e.g. travelling to a foreign country for leisure or on purpose, taking up a 'teach-yourself' language course etc.) and was not widely affordable. The advances in technology have undoubtedly facilitated access to an infinite source of authentic material in many languages expanding the horizons and broadening the possibilities of autonomous learners. Nonetheless, being an out-of-class student requires much more inner force in order to preserve the willingness to learn and overcome difficulties which are normally dealt with within a typical classroom setting. According to recent research, autonomous learners have attained high levels of language proficiency outperforming their in-class counterparts, which challenges formal classroom-based teaching methodology. Irrespective of the learning setting, however, the key to a learner's aim is motivation. It is the fuel that urges learners to excel at their endeavour. What if the foreign language learners were older adults diagnosed with Mild Cognitive Impairment?