Learn Hardcore Finnish: Terotan lyijykynän valmiiksi, jotta voin heti aamulla tehdä kielioppiharjoituksen. - I sharpen the pencil in advance so that I can do a grammar exercise right away in the morning.

Infinitive: terottaa = to sharpen
Conjugation in the present:
- minä terotan – I sharpen
- sinä terotat – you sharpen
- hän terottaa – he/she sharpens
- me terotamme
- te terotatte
- he terottavat

So terotan alone already includes the subject I; that is why minä is not needed in the sentence.

Why is lyijykynän in this -n form? Could I also say lyijykynää?

Lyijykynän is in the genitive/accusative singular and functions as a total object.

lyijykynä = a/the pencil (nominative, dictionary form)
lyijykynän = the pencil as a whole, fully affected by the action

Here, the idea is that you will fully sharpen one specific pencil and finish the job. That is why the “total object” form lyijykynän is used.

If you used lyijykynää (partitive):

Terotan lyijykynää.
→ I’m (in the process of) sharpening a/the pencil.
- The action is seen as ongoing, incomplete, or unbounded.
- It doesn’t say you definitely finish sharpening it.

So:

lyijykynän = whole, completed event (fits the idea of having it ready for the morning)
lyijykynää = partial, ongoing, or indefinite action

What case is valmiiksi, and why is it valmiiksi and not valmiina?

Valmiiksi is in the translative case (-ksi), which often expresses a change of state or end result.

valmis = ready
valmiiksi = into a state of being ready (as a result)

In this sentence, terotan lyijykynän valmiiksi means:

I sharpen the pencil *so that it becomes ready / into a ready state.*

Compare with valmiina (essive case, -na/-nä):

Lyijykynä on valmiina.
→ The pencil is ready (already in that state, static).

So:

valmiiksi – used with verbs of doing/making to show the result of the action
- pestä puhtaaksi – to wash something clean
- maalata punaiseksi – to paint something red
- leikata paloiksi – to cut into pieces
valmiina – describes a state of something
- Lyijykynä on valmiina pöydällä. – The pencil is ready on the table.

Could I just say Terotan lyijykynän, jotta voin heti aamulla tehdä kielioppiharjoituksen without valmiiksi?

Yes, that sentence is grammatically correct and understandable:

Terotan lyijykynän, jotta voin heti aamulla tehdä kielioppiharjoituksen.

The meaning is almost the same: I sharpen the pencil so that I can do the grammar exercise first thing in the morning.

However, valmiiksi adds a nuance:

With valmiiksi:
- Emphasises that you will sharpen it completely in advance, so it is ready and you don’t need to do anything more in the morning.
Without valmiiksi:
- Still implies you sharpen it for that purpose, but the idea of “completely ready beforehand” is less strongly highlighted.

So valmiiksi makes the intention and the completeness of the preparation clearer.

What does jotta mean, and how is it different from että or niin että?

Jotta is a conjunction that introduces a purpose clause and usually corresponds to “so that / in order that” in English.

In the sentence:

... jotta voin heti aamulla tehdä kielioppiharjoituksen.
→ ... so that I can do the grammar exercise first thing in the morning.

Differences:

jotta
- Typical use: express purpose / goal
- More neutral/formal in written language.
- Often used with voida, saada, ehtiä, pystyä, etc.
- Example: Teen läksyt nyt, jotta voin illalla levätä. – I’ll do my homework now so that I can rest in the evening.
että
- Very common, more general “that” / “so that”.
- Frequently used for reported speech:
  - Hän sanoi, että tulee myöhässä. – He said that he will be late.
- In everyday speech Finns often use että where written language prefers jotta:
  - Terotan lyijykynän, että voin heti aamulla tehdä... – Colloquial but natural.
niin että
- Literally “so that”, often for result or consequence, not necessarily for intention:
  - Huusi niin kovaa, että kaikki heräsivät. – He shouted so loud that everyone woke up.
- This is more about what ends up happening, not why you did something on purpose.

In your sentence, jotta is ideal because it clearly marks the clause as expressing your purpose for sharpening the pencil.

Why is voin (present tense) used even though the action happens in the morning (the future)?

Finnish does not have a separate future tense. The present tense is used for:

Present actions
Future actions (when the context makes the time clear)

Here, heti aamulla (“right in the morning”) clearly marks the time as future relative to now, so:

jotta voin heti aamulla tehdä...
= so that I can do it in the morning (future meaning from context)

You could also see:

jotta voisin heti aamulla tehdä...
– “so that I could do...”, conditional, slightly more hypothetical/polite.

But the normal, straightforward way in Finnish is to use present tense plus a time expression instead of a future tense.

Why is the verb tehdä in the basic infinitive form after voin?

Voin is the 1st person singular of voida (can, be able to), a modal/auxiliary verb. In Finnish, many such verbs are followed by the 1st infinitive (dictionary form) of the main verb.

Pattern:

voida + (verb in infinitive)

So:

voin tehdä = I can do
voit tehdä = you can do
hän voi tehdä = he/she can do

Other common verbs that work the same way:

haluan syödä – I want to eat
aion opiskella – I am going to study
osaan uida – I know how to swim

In all these, only the first verb is conjugated for person and tense; the second stays in the infinitive form.

Why is kielioppiharjoituksen in this -n form? What is the difference from kielioppiharjoitusta?

Kielioppiharjoituksen is the genitive/accusative singular form of kielioppiharjoitus and functions as a total object, just like lyijykynän.

kielioppiharjoitus = a grammar exercise (nominative)
kielioppiharjoituksen = the (whole) grammar exercise (genitive/accusative singular)

In the sentence:

... tehdä kielioppiharjoituksen.
→ to do the whole grammar exercise (finish it)

If you used kielioppiharjoitusta (partitive):

Haluan tehdä kielioppiharjoitusta.
→ I want to do (some) grammar exercise / work on grammar exercises (ongoing, not necessarily finish one complete exercise).

So:

kielioppiharjoituksen = one specific exercise, goal is to complete it
kielioppiharjoitusta = ongoing or indefinite work on grammar, not necessarily finishing a specific single exercise

Can I change the order heti aamulla to aamulla heti? Does it change the meaning?

Both heti aamulla and aamulla heti are possible and understandable, but heti aamulla is the more common and natural-sounding expression for “first thing in the morning”.

heti aamulla
- Very common fixed phrase.
- Means roughly “right in the morning / as soon as it’s morning”.
- Sounds smooth and idiomatic here.
aamulla heti
- Also possible.
- Can put a bit more emphasis on aamulla (in the morning (as opposed to another time)), and then add heti (right away) as a clarification.
- Slightly less idiomatic as a fixed collocation, but not wrong.

The basic meaning is essentially the same; the difference is more about rhythm and focus than about a major change in content.

What are lyijykynä and kielioppiharjoitus made of, and how do such compound words behave in Finnish?

Both lyijykynä and kielioppiharjoitus are compound nouns.

lyijykynä
- lyijy = lead
- kynä = pen
  → lyijykynä = pencil (literally “lead pen”)
kielioppiharjoitus
- kielioppi = grammar (literally “language learning/teaching”)
- harjoitus = exercise, practice
  → kielioppiharjoitus = grammar exercise

Key points about compounds:

They are written as one word.
Only the last part of the compound takes the normal case ending:
- lyijykynä → lyijykynän, lyijykynää
- kielioppiharjoitus → kielioppiharjoituksen, kielioppiharjoitusta
The first part may change slightly due to sound rules when it itself is a complex form (e.g. kielioppi
- harjoitus → kielioppiharjoitus, not kielioppiharjoitus with double pph).

In your sentence, lyijykynän and kielioppiharjoituksen are just normal object forms of these compounds.

Why is there no minä in the sentence? Is it wrong to add it?

It’s not wrong to add minä, but it is usually unnecessary.

Finnish is a pro-drop language: the person ending on the verb already shows who is doing the action.

Terotan lyijykynän...
– terotan ends in -n, which marks 1st person singular → “I sharpen...”

You could say:

Minä terotan lyijykynän valmiiksi, jotta voin heti aamulla tehdä kielioppiharjoituksen.

This is grammatically correct, but minä adds emphasis:

“I (as opposed to someone else) sharpen the pencil...”

In neutral, everyday Finnish, you normally leave out minä unless you want that kind of contrast or emphasis.

Is there another, more compact way to express the purpose than jotta voin ... tehdä kielioppiharjoituksen?

Yes. Finnish can also express purpose using the -kse- infinitive (so-called “infinitive of purpose”). For example:

Terotan lyijykynän valmiiksi, voidakseni heti aamulla tehdä kielioppiharjoituksen.

Here:

voidakseni = voida
- -kse-
  - -ni (my)
    → “in order for me to be able to”

This construction is more formal and less common in everyday speech than jotta voin. Your original sentence with jotta voin is perfectly natural and more typical in normal modern Finnish:

Terotan lyijykynän valmiiksi, jotta voin heti aamulla tehdä kielioppiharjoituksen.