Learn Hardcore Esperanto: Mi instruas vin Esperanton.

In Esperanto the direct object of a verb is marked with the accusative ending -n. Since Esperanton is the thing being taught—that is, the direct object—it receives the -n ending to clearly indicate its grammatical role.

What does the verb ending -as in instruas indicate?

The ending -as is one of Esperanto’s standard verb endings that marks the present tense. Therefore, instruas means “teach” (or “is teaching”) in the present.

Why is the pronoun vin used instead of vi in this sentence?

In Esperanto, pronouns change form based on their role in the sentence. Vi is the nominative form meaning “you,” but when used as a direct object—even as the indirect object in double object constructions—it takes the accusative ending, becoming vin.

Does the accusative marking with -n affect word order in Esperanto?

Yes, it does. Because the -n ending clearly marks the object, Esperanto allows for a flexible word order. Even if you rearrange the sentence, the roles of the words remain clear thanks to these consistent endings.

Is there an alternative way to express “I teach you Esperanto” using a preposition?

Absolutely. You could also say Mi instruas Esperanton al vi. In this version, Esperanton remains the direct object (with its -n ending), and al vi explicitly marks “you” as the indirect object. Both constructions are correct and commonly used.

If you wanted to modify Esperanton with an adjective, should the adjective also receive an -n ending?

Yes. In Esperanto, any adjective that directly modifies a noun in the accusative must also take the -n ending to agree in case. For example, to say “I teach you beautiful Esperanto,” you would say Mi instruas vin belan Esperanton.