Learn Hardcore Russian: Учитель объясняет трудную грамматику.

Учитель means "teacher" and is a masculine singular noun. In Russian, the gender of a noun is essential because adjectives and verbs must agree with it in gender (when applicable) and number.

What is the form, tense, and aspect of the verb объясняет?

Объясняет is the third person singular form of the verb объяснять. It is in the present tense and is imperfective, which indicates an ongoing or habitual action.

Why is the adjective трудную in this particular form?

The adjective трудную is in the feminine singular accusative form. It agrees with the noun грамматику (which is feminine) since adjectives in Russian must match the gender, number, and case of the noun they describe. In the accusative case, трудный becomes трудную when modifying a feminine noun.

What case is the noun грамматику in, and why is that case used?

Грамматику is in the accusative case because it functions as the direct object of the verb объясняет. In Russian, the direct object of a transitive verb is typically put in the accusative case, which in this instance reflects that the noun is feminine and singular.

How does the word order in this sentence compare to that in English, and is it flexible?

The sentence follows the typical Russian word order of Subject-Verb-Object (SVO): Учитель объясняет трудную грамматику. Unlike English, Russian allows for more flexibility in word order thanks to its rich system of inflections. The grammatical roles are clear from the word endings, so rearranging the order—for example, to emphasize a particular element—will still convey the correct meaning.