Practical conversation · Formulaic expressions (chunks) + spaced retrieval
Have you heard that memorizing just 300 practical expressions solves 90% of conversation? It is tempting, but no research backs this number. Yet learning formulaic expressions whole does in fact work; only the grounds are different.
After this card, you will know why how you handle expressions matters more than how many, and know concrete training for turning formulaic expressions into real speech.
You received a list of "300 practical expressions." What is the most effective way to study it?
You often see claims that a particular number is a threshold, such as "memorize 300 practical expressions and 90% of conversation is solved." But it is hard to find a corpus analysis or experiment that verified this figure. There is research showing that a few thousand high-frequency words cover a large share of a spoken corpus, but that is about individual words, not a threshold at the level of sentences or expressions. The Korean language standard curriculum also is not built on a number of patterns; it is organized around achievement standards by level and language skills. Rather than relying on numbers, how you handle expressions matters.
Then why is learning formulaic expressions (expressions set as one chunk) effective? Instead of assembling grammar to build a sentence each time, pulling out a frequently used chunk whole frees up that much of the brain, so speaking speed and naturalness rise. This is why second-language (L2) acquisition research holds that formulaic expressions reduce processing load and contribute to fluency. The point is not how many, but how many expressions you have stored whole and can pull out right away.
Reading an expression and feeling "oh, I know this" is a completely different ability from having it come straight out of your mouth at a flustered moment. Linguistics separates these into receptive knowledge (recognizing) and productive knowledge (pulling out to use). If you only repeat reading, only the first grows, and at the moment you need it the words still do not come. So you need practice saying it aloud within 3 seconds, seeing only the situation (without looking at the Korean sentence).
That retrieval practice at intervals (spaced retrieval) lasts longer than cramming repetition is a fact confirmed by a large meta-analysis (98 effect sizes, 48 experiments, 3,411 participants). Pulling out an expression again 1 day, 3 days, 7 days, and 14 days later is far more efficient than seeing today's expression many times only today. Add to this practice as a 2-turn dialogue, attaching the other person's likely reply to one expression, and your chance of using it in a real conversation rises further.
Expressions stay through training in pulling them out, not through their number.
A numeric promise such as "memorize this many and this percent is solved" has no basis. Instead, learn formulaic expressions whole to reduce processing load, practice retrieval by saying them aloud within 3 seconds seeing only the situation, and repeat that practice at 1, 3, 7, and 14 day intervals. Do not treat all 300 with equal weight; automating first the expressions for situations you meet often is the fastest road.