“Classic” TPRS ensured transparency by insisting on translation. It has been argued that simply relying on context is dangerous because students might get the wrong meaning.
The same concern has come up in reading theory: how do we know that readers are arriving at the correct meaning of an unfamiliar word – some contexts are “deceptive” or “misleading.” But: (1) most contexts are not deceptive. Beck, McKeown and McClaslin, (1983) examined contexts in basal readings: 61% providing at least some clues to the meanings of unfamiliar words, 31% were of no help, and only 8% were “misdirective.” (2) We don’t expect full acquisition of a meaning of a word from one exposure; rather, meaning is built up gradually, a little at a time, as we see the word again and again and test” studies discussed in Krashen, 2004, and discussion in Krashen, 2013a.). (3) Acquiring vocabulary from context is the way we have acquired nearly all of our vocabulary. When we consider the thousands of words we know, in L1 or L2, very few were defined or translated for us.