Purpose

By the end of this lesson, you will be able to form and use the instrumental case to express means, accompaniment, and the complement of “to be” in other tenses.

Lesson Explanation

The instrumental case — the sixth and final case in this course’s systematic tour — expresses the means by which something is done, or accompaniment (“with” someone), and one genuinely important structural role connecting back to Part 1, Lesson 5.

Means: Я пишу ручкой. (I write with a pen — “ручкой” instrumental, expressing the tool used, with no preposition needed at all.) Masculine nouns take -ом: стол → столом. Feminine nouns ending in -а take -ой: книга → книгой. Neuter nouns take -ом: окно → окном.

Accompaniment, requiring the preposition с (with) plus the instrumental — genuinely different from the toolless “means” usage above: Я иду с другом. (I’m going with a friend — “другом” instrumental after “с.”)

The genuinely important structural role: recall from Part 1, Lesson 5 that “to be” is absent in the present tense but exists in the past and future (быть, covered fully in Part 4, Lessons 2-3). When “to be” DOES appear with a predicate noun (as opposed to the present tense’s bare nominative pairing), that predicate noun often shifts to the instrumental rather than staying nominative: Он был врачом. (He was a doctor — “врачом” instrumental, not nominative “врач”) — a genuinely important detail that will make full sense once the past tense of быть is introduced.

Practice Questions