一段 Verbs: Class Overview

This is the reference paradigm for the 一段（いちだん）class — the verbs textbooks call "ru-verbs," "Type 2," or "Group 2." It exists to give you one thing the godan class can never offer: a paradigm with zero sound-changes. For every ichidan verb you will ever meet, the recipe is identical — chop off the final る and attach the ending directly to what is left. This page lays out the whole paradigm on the model verb 食べる（たべる, "to eat"）, gives you the reliable test for spotting the class, and flags the two places where ichidan quietly does something godan does not.

The whole class in one sentence

An ichidan verb has a fixed stem. Where a godan stem walks up and down the five vowel rows (書か・書き・書く・書け・書こ), an ichidan stem never moves — you drop る and the bare stem takes every ending as-is:

食べる → 食べ → 食べます ／ 食べない ／ 食べた ／ 食べて

The name 一段 means "one row," and that is the literal mechanic: the stem sits on a single row and stays there. No consonant to track, no euphonic change (音便) to memorize, no exceptions inside the class. This is genuinely the easiest thing to conjugate in Japanese.

The class test: い-row or え-row before る

Every ichidan verb's dictionary form ends in -る, and the kana immediately before that る is always on the い-row (i) or the え-row (e). That is the whole diagnostic:

Contrast that with a godan -る verb such as 作る（つくる, "to make"）or 乗る（のる, "to ride"）: there the kana before る sits on the う-row (u) or お-row (o) — 作る, 乗る — and those verbs keep their る and slide across the rows. So the test cuts cleanly: i/e-vowel before る ⇒ almost certainly ichidan; a/u/o-vowel before る ⇒ always godan.

The full paradigm — 食べる

Here is the complete reference. Every single cell is built the same way: bare stem 食べ + the ending. Compare it, form for form, against a godan table and the appeal of ichidan is obvious — there is nothing to fix along the way.

Two things ichidan does that godan doesn't

For a bare paradigm the class is effortless, but two cells deserve a warning label — they are exactly where English speakers, drilling by analogy with godan, slip.

1. Potential and passive are the same form

Look again at the table: potential 食べられる and passive 食べられる are spelled and pronounced identically. Godan verbs keep them apart (書ける "can write" vs 書かれる "is written"), but ichidan folds both meanings into the single 〜られる. Only context tells them apart:

In casual speech, the potential often sheds its ら — 食べれる, 見れる, 起きれる — the phenomenon called ら抜き言葉 (ra-nuki, informal/spoken). It disambiguates neatly (食べれる can only be potential), but it is still avoided in formal writing.

2. The imperative is 〜ろ, not 〜え

A godan imperative lands on the え-row: 書く → 書け, 話す → 話せ. Do not carry that over. An ichidan imperative replaces る with ろ: 食べろ, 見ろ, 起きろ. (A stiffer literary variant 食べよ survives in written orders and slogans.) Producing ×食べえ is a classic cross-class error.

Common mistakes

Every one of these comes from importing a godan reflex into a class that has none. Once you have confirmed a verb is ichidan, stop thinking — drop る and attach.

Key takeaways

• 一段 = "one row." The stem is fixed; conjugate by dropping る and attaching the ending directly.
• Class test: an i-row or e-row kana before る (見る, 食べる, 起きる) — versus a u/o-row kana for godan -る verbs (作る, 乗る).
• The paradigm has no euphonic sound-changes — no 音便, no exceptions inside the class.
• Potential and passive collapse into one form, 食べられる; casual speech drops the ら (食べれる, ら抜き).
• The imperative is 〜ろ (食べろ), never the godan 〜え. Confirm the class first on godan -る vs ichidan -る, then drill the model on 食べる in full.