No parque, a professora pediu que as crianças esperassem antes de subir no balanço.

No is the contraction of em + o.

• em o parque → no parque
• em a escola → na escola
• em os parques → nos parques
• em as praças → nas praças

Portuguese normally makes these contractions, so em o parque would sound wrong in standard Portuguese.

Portuguese usually uses definite articles much more often than English does.

So a professora is the normal way to say the teacher. In a sentence like this, it refers to a specific teacher in that situation.

English sometimes leaves articles out in places where Portuguese would not, but here Portuguese strongly prefers a professora, not just professora.

Because the sentence is talking about a specific group of children, not children in general.

• as crianças = the children / those children
• crianças = children in general, or a less specific mention

In this context, the teacher is speaking to particular children at the park, so as crianças is the natural choice.

Yes, you could also hear pediu para in Brazilian Portuguese.

The structure in the sentence, pediu que + subjunctive, is very standard:

• A professora pediu que as crianças esperassem...

A very common Brazilian alternative is:

• A professora pediu para as crianças esperarem...

Both are natural. The version with que is often felt to be a bit more formal or more textbook-like, while para + infinitive is very common in everyday speech.

Because pedir que normally triggers the subjunctive.

Here, the main verb is in the past:

• pediu = asked

So the subordinate verb usually goes into the imperfect subjunctive:

• esperassem = that they wait / waited, in a requested or desired sense

Compare:

• A professora pede que as crianças esperem.
  The teacher asks that the children wait.
• A professora pediu que as crianças esperassem.
  The teacher asked that the children wait.

So esperassem is not just a past tense; it is specifically the form expected after a past-tense verb of request.

The ending shows it.

Esperassem is the third-person plural imperfect subjunctive form of esperar, so it matches as crianças.

A quick pattern:

• eu esperasse
• você/ele/ela esperasse
• nós esperássemos
• vocês/eles/elas esperassem

Since as crianças is plural, esperassem is the correct form.

After antes de, Portuguese normally uses an infinitive if the idea is before doing something.

So:

• antes de subir = before getting on / before going up onto

This is very common:

• antes de sair = before leaving
• antes de comer = before eating
• antes de falar = before speaking

Using an infinitive after antes de is one of the most basic and natural patterns in Portuguese.

This is a very good question, because both can appear.

In everyday Brazilian Portuguese, antes de subir is very common when the subject is already clear from context. Here, we understand that it is the children who are going to get on the swing.

But you may also hear or see:

• antes de subirem no balanço

That form, subirem, is the personal infinitive, and it makes the subject more explicit.

So:

• antes de subir no balanço = common and natural
• antes de subirem no balanço = also correct, a bit more explicit, and sometimes preferred by careful speakers because the subject is as crianças, not a professora

Yes, subir literally means to go up, to climb, or to get onto something.

With playground equipment, Brazilian Portuguese often uses subir em/no for getting onto it. So subir no balanço is a natural way to say get on the swing.

It is not always a word-for-word match with English. In English, we say get on the swing; in Portuguese, subir no balanço is a very normal way to express that idea.

The singular is natural here because it refers to the activity or to the swing each child is waiting to use.

So subir no balanço can mean something like get on the swing in a general situation.

If you wanted to emphasize multiple swings, you could say:

• nos balanços = on the swings

But the singular sounds completely normal in a sentence like this, even at a playground where there may be more than one swing.

Yes. Portuguese word order is fairly flexible.

The sentence begins with No parque to set the scene first:

• No parque, a professora pediu que as crianças esperassem...

You could also say:

• A professora pediu, no parque, que as crianças esperassem...
• A professora pediu que as crianças esperassem antes de subir no balanço, no parque.

But the original version sounds very natural because No parque works well as a scene-setting phrase at the beginning.