Learn Hardcore Russian: Я пишу конспект, когда учитель говорит.

In Russian complex sentences, the main clause and a subordinate clause introduced by когда are always separated by a comma. Here Я пишу конспект is the main clause, когда учитель говорит is the subordinate clause.

Why is конспект in the singular and not plural?

Конспект refers to one continuous set or notebook of notes. Even though you may take many notes, they form a single summary. You’d use the plural конспекты only if you meant several distinct summaries.

What’s the difference between писать конспект and конспектировать?

Both mean “to take notes.”

писать конспект is more colloquial and literally “to write a summary.”
конспектировать is a single verb, more formal or bookish, and less common in everyday speech.

Why is пишу in the imperfective aspect rather than the perfective?

The imperfective писать indicates an ongoing or habitual action (“I am writing/taking notes”). A perfective verb like написать конспект would imply completing the notes, e.g. “I will finish taking notes when the teacher speaks,” which changes the meaning.

Why is говорит in the present tense?

This sentence describes two simultaneous actions: “I write notes while the teacher speaks.” Both verbs are in the present tense to show they occur at the same time now or habitually.

Can I swap the clauses and say Когда учитель говорит, я пишу конспект?

Yes. You can start with either clause. The comma rule remains the same. The meaning is identical; starting with когда just shifts the emphasis slightly to the time frame.

Could I use пока instead of когда here?

Yes. пока also means “while” for simultaneous actions:
Я пишу конспект, пока учитель говорит.
Both are correct, though пока is often a bit more conversational.

Why is учитель in the nominative case?

In the subordinate clause когда учитель говорит, учитель is the subject performing the action говорит, so it takes the nominative case.

Can I omit учитель and say Я пишу конспект, когда говорит?

No. Russian requires a clear subject in the subordinate clause. You could say когда он говорит (“when he speaks”) if the context has already introduced он as “the teacher,” but you can’t drop the subject entirely.

Does this sentence imply a one-time event or a habitual action?

With imperfective verbs in the present tense, it usually describes a habitual or recurring situation: “Whenever the teacher speaks, I take notes.” For a one-time event in the past, you’d switch to past tense (e.g., Я писал конспект, когда учитель говорил).