Learn Hardcore Swedish: Under nästa lektion vill jag prata bara svenska. - During the next lesson I want to speak only Swedish.

Swedish is a V2 language (verb-second). That means the finite verb (here vill) almost always comes in second position in a main clause.

When you put something other than the subject first (like a time expression), word order changes:

Jag vill prata bara svenska.
→ Subject (jag) is first, verb (vill) is second.
Under nästa lektion vill jag prata bara svenska.
→ Time phrase (Under nästa lektion) is first, so the verb (vill) must still be second, and the subject (jag) comes after it.

Both word orders are correct; they just emphasize different parts. Starting with Under nästa lektion highlights the time frame.

Can I also say Jag vill under nästa lektion prata bara svenska?

Yes, that word order is grammatically correct, but it sounds a bit more formal or written.

Natural alternatives:

Under nästa lektion vill jag bara prata svenska. (very natural)
Jag vill bara prata svenska under nästa lektion. (very natural)

Putting the time phrase between the modal verb (vill) and the main verb (prata) is possible, but it’s more marked and less common in everyday speech.

Why is it nästa lektion and not nästa lektionen?

In Swedish, words like nästa (next), förra (last), den här / denna (this) already make the noun definite, so you normally don’t also use the definite ending -en / -n / -et / -t on the noun in time expressions.

So you say:

nästa lektion – next lesson
förra veckan – last week
den här terminen – this term

If you said nästa lektionen, it would sound wrong here because that would be a kind of “double definiteness” in this context.

You can have lektionen on its own:

Lektionen börjar nu. – The lesson is starting now.

Can I say i nästa lektion or på nästa lektion instead of under nästa lektion?

For the meaning “during the next lesson,” the natural choices are:

Under nästa lektion – literally “during next lesson,” very clear.
På nästa lektion – literally “at the next lesson,” also very common.

I nästa lektion normally sounds wrong in this context.

Subtle nuance:

Under nästa lektion focuses on the whole time span (“all through that lesson”).
På nästa lektion focuses more on the occasion/event (“at that class/at that time”).

In everyday speech, both Under nästa lektion and På nästa lektion are fine for this sentence.

Why is it nästa and not a different form agreeing with lektion?

Nästa is an invariable form when it’s used as a determiner meaning “next” in time expressions. It doesn’t change for gender (en/ett), number (singular/plural), or definiteness in phrases like:

nästa lektion (en-word)
nästa år (ett-word)
nästa gång (en-word)
nästa vecka (en-word)

So you always use nästa, not nässt, näste, etc., in this function.

What does vill add here? Could I just say Under nästa lektion pratar jag bara svenska?

You can say both, but there is a nuance:

Under nästa lektion pratar jag bara svenska.
→ Present tense used with a future meaning, like English “I’m only speaking Swedish next lesson.” It sounds like a plan/schedule or prediction.
Under nästa lektion vill jag bara prata svenska.
→ Literally “I want to only speak Swedish during the next lesson.” It expresses a wish/intention more explicitly.

So vill makes it clear that this is something you want, not just a neutral description of what will happen.

What is the difference between prata and tala?

Both mean “to speak”, but they differ in tone/register:

prata – more informal, everyday. Very common in speech.
→ Jag vill prata svenska.
tala – more formal or careful, often used in:
- formal contexts (speeches, official information)
- set phrases (tala sanning, tala sanning etc.)

In your sentence, prata is the most natural in ordinary conversation.
A bit more formal version would be:

Under nästa lektion vill jag tala bara svenska. (grammatically fine but sounds more formal/stiff in everyday speech)

Why is it prata svenska and not prata på svenska?

Both prata svenska and prata på svenska exist, but they’re used slightly differently.

prata svenska – the normal, neutral way to say “speak Swedish.”
→ Jag vill prata svenska.
prata på svenska – often emphasizes the medium/language: speak in Swedish. It’s used, for example, when switching languages or explaining:
- Kan vi prata på svenska i stället? – Can we speak in Swedish instead?
- Hur säger man det på svenska? – How do you say that in Swedish?

In your sentence, prata svenska is exactly what you want because you are talking about the language you want to use generally during the lesson.

Is prata bara svenska the best word order, or should it be bara prata svenska?

Both are possible, but they focus slightly differently and some orders are more common:

Most natural for “only speak Swedish”:

Under nästa lektion vill jag bara prata svenska.
→ bara comes before the verb prata and clearly limits the action “speak”.

Your original:

Under nästa lektion vill jag prata bara svenska.
→ bara is right before svenska, so it focuses more on the object (“only Swedish” as opposed to other languages). It’s understandable and not wrong, but word order with bara before the verb is usually more common:

Compare:

Jag vill bara prata svenska. – I only want to speak Swedish.
Jag vill prata bara svenska. – I want to speak only Swedish. (fine, but a bit less typical)

In practice, you’ll hear both, but …vill jag bara prata svenska is probably the most idiomatic.

What is the difference between bara and endast?

Both can mean “only”, but they differ in register:

bara – informal, everyday. Very common in speech and writing.
- Jag vill bara prata svenska.
endast – formal or bureaucratic; common in official texts, signs, instructions:
- Endast personal. – Staff only.
- Betalning sker endast med kort. – Payment only by card.

In a spoken sentence like yours, bara is definitely the natural choice:

Under nästa lektion vill jag bara prata svenska.

Why is it just svenska and not svenskan or det svenska språket?

When you say you speak a language in Swedish, you normally use the indefinite form without any article:

prata svenska – speak Swedish
prata engelska – speak English
prata tyska – speak German

You use svenskan (definite) when talking about “the Swedish language” as a subject:

Svenskan har många dialekter. – Swedish has many dialects.

And det svenska språket is even more explicit and formal:

Det svenska språket är svårt. – The Swedish language is difficult.

In your sentence, you’re talking about using the language, so the normal form is just svenska without an article.

How would the sentence change if I made it negative with inte?

The position of inte in Swedish is important and follows set patterns.

With a modal verb (vill) plus an infinitive (prata), inte usually comes after the finite verb:

Under nästa lektion vill jag inte prata svenska.
→ “During the next lesson I don’t want to speak Swedish.”

If you still want to keep bara:

Under nästa lektion vill jag inte bara prata svenska.
→ “During the next lesson I don’t want to only speak Swedish.”
(Implied: you want to do other things too, e.g. speak English as well.)

So the core rule: finite verb (vill) is second, and inte normally comes directly after the subject (jag) or after the finite verb, depending on structure. In this sentence, vil[l] jag inte prata… is the natural order.