Cuando la profesora empieza a hablar, nos callamos enseguida.

when

Breakdown of Cuando la profesora empieza a hablar, nos callamos enseguida.

• nosotros: we
• a: to
• la profesora: the teacher

Questions & Answers about Cuando la profesora empieza a hablar, nos callamos enseguida.

Why is cuando followed by the present tense here?

Because this sentence describes a habitual or general situation: whenever the teacher starts talking, we go quiet.

In Spanish, with cuando, you often use the present tense for repeated actions:

• Cuando la profesora empieza a hablar, nos callamos enseguida.
• Cuando llego a casa, ceno.

This is similar to English when/whenever in general statements.

Also, Spanish often uses the present after cuando even for the future:

• Cuando llegue, te llamo.
  = When he/she arrives, I’ll call you.

So the present after cuando is very common.

Why is it la profesora and not just profesora?

Here, la profesora means the teacher: a specific teacher that both speaker and listener can identify.

Spanish usually uses the definite article when referring to a specific person by role or title:

• La profesora entra en clase.
• El médico ya viene.

But after ser, professions normally appear without an article:

• Es profesora.
• Soy médico.

So:

• la profesora = the teacher
• es profesora = she is a teacher