Verb classifications by japanese learners

Question

As a studies of Japanese I've come across two distinct ways to group verbs for purposes of remembering how to conjugate them.

う動詞 / る動詞
Group1 / Group 2

Pacerier mentioned a verb1 and verb5, can someone explain to me how the verbs are divided for this system?

Also, how do Japanese people learn the different conjugations patterns? What system for verb classification do they use?

this question may boarder on off-topic, but i think as a Japanese learner, I'd like to be able to ask verb related questions to a Japanese person, but if i say う動詞, unless they are familiar with non-foreigners learning Japanese, they don't know what I'm talking about.

Answer 1

The two types are:

[五段動詞]{ご・だん・どう・し} ー means "5-level verbs". This is the group where the conjugations match the 5 vowel sounds of their respective kana ending. A common 五段動詞 is 書く. It conjugates along the k- column of the hiragana table:

書かない　　書きます　　書く　　書けば／書ける　　書こう

We can see that its conjugations hit all 5 of the k-kana:   か　き　く　け　こ

Note that 五段動詞 that end in 〜う (like 会う) have a conjugation of わ　い　う　え　お  (会わない for the negative). This is not arbitrary, and there are historical reasons for this, but I will not attempt to get into them here.

The other type are the [一段動詞]{いち・だん・どう・し} (your るverbs). However, these can be broken down based on (I believe) the last character of their "base form" (the part before the る). The kana columns go -a -i -u -e -o, where the -u is considered the "center". They are classified as "upper" ([上]{かみ}) or "lower" ([下]{しも}) based on the center.

• 着る is 上一段 since き is one level "above" the center (which would be く)
• 食べる is 下一段 since べ is one level "under" the center (which would be ぶ)

There are such things as 上二段 and 下二段 verbs, but I don't think they exist in modern spoken Japanese. At least that's what 広辞苑 implies.

Answer 2

The two main classifications of regular verbs are 一段 and 五段, named after the number of forms their base takes.

• 食べる -> 食べ
• 入る -> 入ら・入り・入る・入れ・入ろ

Within 一段 there are two further classifications, although both are conjugated the same way.

• 上一段: 見る, 落ちる, etc.
• 下一段: 寝る, 当てる. etc.

Answer 3

There is a pretty good and complete overview of the two groups (一段/五段, which can also be seen as "U-dropping" and "RU-dropping" in romaji) on this page.

する and くる have separate, exception-filled, conjugations of their own (sometimes referred to as サ行変格活用/カ行変格活用).

Note that, like many technical grammatical question, I really don't think you will get a very useful answer from a non-specialist native. Japanese verb conjugation rules are fairly straightforward (though filled with exceptions) and most Japanese simply "know" which is which, without necessarily knowing why. Quite the same way your average English speaker would be at a loss explaining which verbs are regular and which aren't, and how irregular verbs work.