La profesora escribió el título en la pizarra con tiza y luego nos pidió que volviéramos al aula en diez minutos.

Here la profesora means the teacher.

A common trap for English speakers is that Spanish profesor/profesora is much broader than English professor. In Spain, profesor/profesora is a normal word for a teacher, especially in secondary school and often in general educational contexts.

So in this sentence, la profesora is simply the female teacher.

Escribió is the preterite, which is used for a completed action in the past.

Here, the sentence tells a sequence of finished events:

• she wrote the title
• then she asked us to come back

So escribió fits that narrative of single completed actions.

If you said escribía, that would sound more like:

• she was writing
• she used to write
• it was background information rather than a completed event

So La profesora escribió... means she wrote it as one finished action.

Because Spanish en often covers both in and on, depending on context.

With surfaces like boards, walls, pages, or screens, Spanish often uses en where English uses on:

• en la pizarra = on the board
• en la pared = on the wall
• en la página = on the page

So this is completely normal Spanish usage.

Con tiza means with chalk in a general, material/instrument sense.

Spanish often leaves out the article when the focus is on the substance or means rather than on one specific object:

• escribir con tiza = to write with chalk
• cortar con cuchillo can sometimes mean with a knife, in a general way
• hecho a mano = made by hand

If you say con una tiza, that sounds more like with a piece of chalk / with one chalk stick, making it more specific.

So:

• con tiza = with chalk
• con una tiza = with a piece of chalk

Nos means us.

More exactly, it is the indirect object pronoun here:

• pidió = asked
• nos pidió = asked us

The full idea is she asked us that we return to the classroom, which English normally expresses as she asked us to return to the classroom.

You can compare:

• me pidió = asked me
• te pidió = asked you
• nos pidió = asked us
• les pidió = asked them / you all

After verbs of asking, ordering, wanting, or recommending, Spanish very often uses:

verb + que + subjunctive

So:

• pidió que volviéramos = she asked that we return / she asked us to return

The verb pedir commonly triggers the subjunctive when what follows is a requested action:

• Me pidió que esperara. = She asked me to wait.
• Nos pidió que saliéramos. = She asked us to leave.

The que introduces the subordinate clause, and the subjunctive is used because this is not just a fact being reported; it is something requested.

Because volviéramos is imperfect subjunctive, while volveríamos is conditional, and they mean different things.

Here the teacher is expressing a request, so Spanish uses the subjunctive:

• pidió que volviéramos = she asked us to return

But volveríamos means we would return, which is not the same thing:

• Dijimos que volveríamos. = We said we would return.

So:

• volviéramos = subjunctive, used after pidió que
• volveríamos = conditional, used for would return

This is a very common question.

Aula is indeed a feminine noun, but because it begins with a stressed a sound, Spanish uses el in the singular to avoid the awkward sound of la aula.

So you say:

• el aula
• al aula = a + el

But the noun is still feminine, which you can see in adjectives:

• el aula vacía = the empty classroom

So in this sentence:

• volver al aula = return to the classroom

That al is just the contraction of a + el.

Here en diez minutos means in ten minutes, that is, after ten minutes.

So the idea is:

• the teacher asked us to return to the classroom ten minutes later

This is different from a duration:

• durante diez minutos = for ten minutes

So:

• volver en diez minutos = come back in ten minutes
• esperar durante diez minutos = wait for ten minutes

Because the imperfect subjunctive is built from the preterite stem, not from the present-tense stem.

You may know:

• vuelvo = I return
• volvemos = we return

But the preterite is:

• volví
• volviste
• volvió
• volvimos
• volvieron

From the ellos preterite form volvieron, you remove -ron and add the imperfect subjunctive endings:

• volviera
• volvieras
• volviéramos
• etc.

So volviéramos is correct, and the ue of vuelvo does not appear here.

The accent marks show where the stress goes.

For example:

• título → stress on the first syllable: TÍ-tu-lo
• escribió → stress on the last syllable: es-cri-BIÓ
• pidió → stress on the last syllable: pi-DIÓ
• volviéramos → stress on é: vol-vi-É-ra-mos

In verbs, accent marks are often especially helpful because they distinguish specific forms:

• escribio would be wrong
• escribió is the correct past tense he/she wrote

So the accents are not optional; they are part of the correct spelling and pronunciation.