In Korean Digital Academy, Rob Julien describes verb conjugation with the clock theory. In “Mastering Conversational Korean: Korean for Beginners”, they describe verb conjugation in chapter 6. The “Pattern 5” is equivalent to the clock theory.
Basically, it takes verbs and breaks them into three categories.
How do you get the “changed form” of the verb stem?
- Figure out what category of verb and add 아 / 어 / 여.
- Then do vowel contraction, to get to the changed form.
For example, 오다 would be 오 + ㅏ => 와 changed form.
Just so happens that “ㅏ” verbs stay the same when you add the -아. Here are the vowel contractions for the rest of the verbs except hada verbs.
So verbs with ㅏ, ㅓ, ㅐ, ㅔ won’t change. Phew. So you only have to remember to change ㅗ, ㅜ, ㅡ, ㅣ.
The last category is hada verbs with unchanged 하 and changed form 해.
|가||가||가다 to go|
|보||봐||보다 to watch|
|배우||배워||배우다 to learn|
|먹||먹||먹다 to eat|
|쓰||써||쓰다 to write|
|하||해||노래하다 to sing|
Now conjugate into past, present, and future.
Refer to Korean Digital Academy Video #18b: Conjugation Practice and Review.