Every serious candidate accumulates errors. Almost nobody keeps them.
A mistake notebook is the single highest-return habit in exam preparation, because it is the only study material that is perfectly targeted: it contains nothing you already know.
What goes in it
One line per error, from anywhere - mocks, past papers, class, a textbook exercise, a conversation that went wrong.
Each entry needs three parts:
The item - 待ちます / 持ちます My error - chose 持 for “wait at the station” The cause - look-alike kanji, shared component 寺
The third part is what makes it work. “I got it wrong” is not information. “I confuse these two because they share a component” is a fixable diagnosis.
What does not go in it
Words you simply did not know. Those belong in your vocabulary system - see flashcard app or notebook.
The mistake notebook is for errors of confusion: two things you can tell apart in theory and mix up in practice. Those are the ones that repeat.
Review it on a schedule
The notebook is worthless unread. Two fixed slots:
- Weekly, ten minutes, the week’s entries.
- Before every mock test, the whole thing. This is the highest-yield ten minutes in your preparation, because these are the exact errors you are statistically most likely to make again.
Sort by cause after a month
Once you have thirty or forty entries, group them. The groups are diagnostic:
| Cause group | What it means |
|---|---|
| Look-alike kanji | Recognition is shape-based, not component-based |
| Particles | A grammar gap, not a vocabulary one |
| Heard the wrong number | Listening needs number drilling |
| Ran out of time | Pacing problem, not knowledge |
| Chose a true-but-unstated option | Reading technique |
Each group has a different fix, and none of them is “study harder”. A month of entries tells you which fix you need.
It works for any exam
The method transfers unchanged to JFT-Basic, where the error patterns are narrower and therefore even more repetitive: how to review a mock test.
Sit a full timed paper - the free exam demo for JFT-Basic, past papers for JLPT - and the notebook writes itself.
One notebook, not five
Not one per skill, not one per textbook. One, carried everywhere, in whatever format you will actually use.
The value is entirely in the reviewing, and you will not review five.