This is the 868th most frequent Finnish word.
lapsista
"Lapsista" means "of the children" or "about the children" in English.
'lapsista' here is in the partitive plural form, used with the verb 'kysyi' (asked) to refer to asking questions to the group 'children'.
Opettaja kysyi kaikilta lapsista, mikä heidän lempipelinsä on.
The teacher asked all of the children about their favorite game.
'lapsista' functions here as a partitive plural form, indicating 'of the children', referring to identifying one individual within the group of children.
Yksi lapsista osaa jo soittaa pianoa erittäin kauniisti.
One of the children already plays the piano very beautifully.
Here, 'lapsista' means 'of the children' and is used in the context of referring to partitive plurality within a partitive sense.