Learn Hardcore Finnish: Äiti laittaa lapselle takin päälle.

Äiti = mother (nominative, subject)
laittaa = puts / is putting
lapselle = to the child / for the child / onto the child
- lapsi = child
- -lle (allative case) = to, onto, for (a person)
takin = the coat (genitive form of takki)
päälle = onto (the top, onto the body)

A very literal gloss is:

Mother puts to-the-child the-coat onto.

Natural English:
The mother puts a coat on the child.

Why is it lapselle and not lapsi, lapsen, or lasta?

Lapselle is in the allative case (ending -lle). Allative often means:

to someone, for someone
onto something/someone

Here it marks the recipient/beneficiary of the action:

Äiti laittaa lapselle… = Mother puts (it) on the child / for the child.

Why not the other forms?

lapsi (nominative) – used for the subject of the sentence, but here the child is not the subject.
lapsen (genitive) – usually possessor (the child’s…), or a total object in some structures.
- Äiti pukee lapsen. = Mother dresses the child. (here lapsen is the direct object)
lasta (partitive) – would be a partitive object (e.g. dressing the child (in progress / not completed)), not the role we need here.

So lapselle nicely expresses “onto / for the child”, which matches the meaning: the coat ends up on the child.

Why is takin in the genitive form and not takki or takkia?

Takin is the genitive singular of takki (coat). It is used here for two reasons:

With the postposition päälle
Postpositions like päälle (onto) normally take the genitive of the noun:
- pöydän päälle = onto the table
- tuolin päälle = onto the chair
- takin päälle = onto the coat / onto (one’s) coat
Total object form of a concrete thing
When you are fully putting a specific coat on (a complete action), Finnish often uses the genitive as the “total object”:
- Äiti laittaa takin. = Mother puts the coat (on).
- Äiti osti auton. = Mother bought the car.

Here takin päälle functions as a unit: literally onto the coat. Idiomatically it means on (someone’s) body as a coat.

Takki (nominative) would normally be subject form, not correct here after päälle.
Takkia (partitive) would imply something like an incomplete or ongoing action (putting on a coat, not completed), and still would not fit well directly before päälle in this construction.

What exactly does päälle mean here?

Päälle is a form of pää, meaning head, top, surface. As päälle (allative form), it is a postposition or adverb meaning:

onto, on top of, onto (a surface)

Some examples:

laittaa kirjan pöydän päälle = put the book onto the table
istua tuolin päälle = sit onto the chair
laittaa takin päälle = put a coat on (onto oneself / someone)

In clothing contexts, päälle has become an idiomatic way to say “put on (clothes)”:

Laitan takin päälle. = I put my coat on.
Äiti laittaa lapselle takin päälle. = The mother puts a coat on the child.

So while literally it is onto the coat / onto the top, idiomatically with clothes it just means on (the body).

Why is the phrase takin päälle and not päälle takin?

Finnish postpositions almost always follow the noun they belong to and the noun appears in genitive:

pöydän päälle (onto the table), not päälle pöydän
tuolin alle (under the chair), not alle tuolin
takin päälle (onto the coat/onto the body), not päälle takin

So the order noun (in genitive) + postposition is the normal and essentially fixed pattern.

Päälle takin sounds clearly wrong to a native speaker in this meaning.

Is Äiti laittaa lapselle takin päälle more like “puts a coat on the child” or “puts the child’s coat on”?

It is naturally understood as:

“(The) mother puts a/the coat on the child.”

Finnish does not mark the article (a / the) explicitly, so it can be any coat that context allows:

If context says “they’re going out, so she’s putting on his coat”, then listeners understand it that way.
If context is generic, it’s just a coat.

The sentence itself does not explicitly say that the coat belongs to the child. If you want to be explicit, you could say:

Äiti laittaa lapsen takin lapselle päälle.
= Mother puts the child’s coat on the child.

But usually that is unnecessary; context is enough.

Can I drop lapselle and just say Äiti laittaa takin päälle?

Yes, you can. Then the most natural interpretation is:

Äiti laittaa takin päälle.
= Mother puts (her own) coat on. / Mother is putting on a coat.

In this version:

There is no explicit recipient, so it is interpreted as the subject herself putting on the coat.
Päälle in this kind of sentence is normally understood as “on herself”.

If you include lapselle, you explicitly say she is putting the coat on the child, not on herself:

Äiti laittaa lapselle takin päälle.
= Mother puts a coat on the child.

Why use laittaa here and not pukea or panna?

All three verbs exist, but they differ slightly:

laittaa
- Core meaning: to put, to place, to put on
- Very common in everyday speech for clothes:
  - laittaa takin päälle = put a coat on
  - laittaa hatun päähän = put a hat on (one’s head)
- Neutral, colloquial-sounding, very natural.
pukea
- Core meaning: to dress (someone), to clothe
- Focuses more on the act of dressing:
  - Äiti pukee lapsen. = Mother dresses the child.
  - Äiti pukee lapselle takin. = Mother puts a coat on the child (dresses the child in a coat).
- A bit more “directly about dressing” than laittaa.
panna
- Also to put, to place.
- In many dialects and colloquial speech it can replace laittaa:
  - Äiti panee lapselle takin päälle.
- However, in standard / careful Finnish, laittaa is more neutral, and panna has additional slang/sexual senses, so learners are usually safer using laittaa.

So Äiti laittaa lapselle takin päälle is perfectly natural, everyday Finnish for Mother puts a coat on the child.
You could also say Äiti pukee lapselle takin, which is close in meaning but lacks the päälle construction.

What are the grammatical roles (subject, object, etc.) of each word in the sentence?

In Äiti laittaa lapselle takin päälle, the roles are:

Äiti
- Case: nominative
- Role: subject (the one doing the action)
laittaa
- Verb: 3rd person singular present (he/she puts)
- Role: main verb / predicate
lapselle
- Case: allative (-lle)
- Role: indirect object / recipient / beneficiary
  - to / for / onto the child
takin
- Case: genitive
- Role: direct object (the thing being put on)
päälle
- Postposition / adverb
- Role: directional adverbial (where the object is put: onto (the body))

Together, takin päälle works almost like a single phrase: as a coat, onto (the body).

How would I say “The mother is dressing the child” without mentioning the coat specifically?

The most straightforward option:

Äiti pukee lapsen.
= Mother is dressing the child.

Here:

pukee is from pukea = to dress (someone).
lapsen is genitive functioning as the direct object (the child is being dressed).

This sentence focuses on the action of dressing in general, without specifying which clothes.

By contrast:

Äiti laittaa lapselle takin päälle.
focuses specifically on putting a coat on the child.