Learn Hardcore Swahili: Baada ya mapumziko, tutaimba wimbo darasani. - After the break, we will sing a song in the classroom.

Swahili has no articles. Baada ya mapumziko can mean either after the break or after a break, depending on context. To make it specific, use a demonstrative or a more specific noun:

Baada ya kipumziko kile = after that particular break
Baada ya mapumziko hayo = after that break/recess
Baada ya mapumziko ya mchana = after the lunch break

Can the time phrase move, or must it come first?

You can place it at the beginning or the end. Both are natural:

Baada ya mapumziko, tutaimba wimbo darasani.
Tutaimba wimbo darasani baada ya mapumziko. Fronting the time phrase slightly emphasizes the timing.

Why is it always baada ya and not something that agrees with the following noun?

Baada ya is a fixed prepositional expression meaning after. The ya does not change with noun class. Same with kabla ya (before).

baada ya kazi, baada ya miaka mitatu, baada ya kuimba
kabla ya mchezo, kabla ya kuanza

What exactly does mapumziko mean? Is it singular or plural? Could I use kipumziko?

mapumziko (class 6) literally means rest/break(s) and is often used in the plural to refer to break/recess in general.
kipumziko (class 7) refers to one specific break. Both are fine; choose based on whether you mean a general recess or a particular break:
Baada ya mapumziko (after the break/recess time)
Baada ya kipumziko (after a specific break)

How is tutaimba built, and what does it convey?

It’s subject + tense + verb:

tu- (we) + -ta- (future) + -imba (sing) = tutaimba (we will sing / we’re going to sing). It’s a neutral future; it can be planned or expected. For a more immediate “about to,” you might say tuko karibu kuimba.

How do I negate it: “We will not sing after the break”?

Use the negative subject prefix with the future:

Hatutaimba baada ya mapumziko. With the full sentence: Hatutaimba wimbo darasani baada ya mapumziko.

Do I need to say wimbo, or can I just say tutaimba?

You can drop it. Kuimba works fine intransitively:

Tutaimba darasani. Adding wimbo is also common and a bit more explicit:
Tutaimba wimbo darasani.

How do I say it in the plural: “We will sing songs”?

The plural of wimbo (class 11) is nyimbo (class 10):

Tutaimba nyimbo darasani.

How do I say “this/that song”?

Use class-appropriate demonstratives for wimbo (class 11):

wimbo huu = this song
wimbo huo = that song (near you/just mentioned)
wimbo ule = that song (far/previously mentioned) Example: Baada ya mapumziko, tutaimba wimbo ule.

How do I say “We’ll sing it” without repeating wimbo?

Use the class 11 object marker -u-:

Tutauimba. = We will sing it (the song). If you keep the noun, you normally drop the object marker:
Tutaimba wimbo ule. If you front the object for emphasis, you include both:
Wimbo ule, tutauimba.

What does darasani literally mean? Are there alternatives?

darasani = in the classroom/in class. It’s darasa (class/classroom) + the locative suffix -ni. Alternatives:

katika darasa = in the classroom (neutral)
ndani ya darasa = inside the classroom (emphasizes interior)
shuleni = at school (broader location)

How do I say “before the break” instead?

Replace baada ya with kabla ya:

Kabla ya mapumziko, tutaimba wimbo darasani.

Is the comma after mapumziko necessary?

No. It’s optional for readability. Both are fine:

Baada ya mapumziko tutaimba wimbo darasani.
Baada ya mapumziko, tutaimba wimbo darasani.

Can I say “after singing” instead of “after the break”?

Yes. Use baada ya + infinitive:

Baada ya kuimba, tutaendelea na somo.

How would I ask “Will we sing a song in class after the break?”

Two common ways:

Je, tutaimba wimbo darasani baada ya mapumziko?
Tutaimba wimbo darasani baada ya mapumziko? (question intonation)