We all want more and better output from our students, but how does that happen? The iceberg is students’ total acquisition. The part above the water line is what they can say and write–the messages they can produce. The bigger part under water is what students can comprehend by listening and reading–the messages they can understand.
If the iceberg is a reasonable analogy for language acquisition, there is only one reliable way to do that: make the whole iceberg bigger. The top of the iceberg increases when the bottom gets bigger. The more students understand, the more they will be able to produce.
Trying to lift the whole iceberg to increase the part above water would not only be extremely difficult and time-consuming, it would likely break up the entire iceberg. Conscious learning by memorized lists, formulas and out-of-context drills is like trying to lift the iceberg. It may result in production, but it is not natural or sustainable. If we attempt to increase students’ production without giving them more comprehensible input most of them will not be able or willing to keep on learning the language.