Context matters for learning. We remember better when we are in the same context as we were when we learned. What exactly counts as context? The visual and auditory environment, our state of mind (including mind-altering substances), even the color of the paper used for studying and testing. It's not clear what all the contributing factors are, or to what extent each factor impacts learning. However, since we will often, in real situations, not have the original context available, we will achieve better results by varying the context, contrary to the usual advice to always study according to an exacting routine with as little variation as possible (Carey, 2014).
This doesn't take into account student affect, though it's plausible that, for at least some people, varied study environments will also have a positive impact on that.
Extensive reading could be reasonably effective for vocabulary acquisition, providing exposure to the most common 1000-2000 words a useful number of times, but it becomes less practical for rarer words. News articles seem to give the best variety of words, as compared with fiction and academic articles (Cobb, 2007).
Mozi, a Chinese philosopher from around the fifth century B.C., suggested a set of three criteria for testing claims:
These criteria don't necessarily get at truth, but Mozi may not have distinguished between what we would call truth and merely 'beneficial opinion' (Melchert & Morrow, 2018, pp. 77–80).