Learn Polish: Pamiętaj, żeby ostrożnie zapiąć pasy przedszkolakowi w foteliku. - Remember to carefully fasten the preschooler's seatbelt in the child seat.

Polish frequently uses the dative case to show who is directly affected by an action, especially when dealing with body parts, clothing, or personal equipment. Instead of expressing possession like 'fasten the preschooler's belt' with the genitive, Polish effectively says 'fasten the belt for the preschooler' using the dative.

Why is żeby followed by the infinitive zapiąć instead of a past tense verb?

When the subject of the main clause and the subordinate clause are the exact same person, żeby is followed by an infinitive. Since the person remembering is also the person who will fasten the seatbelt, the infinitive is required. If you wanted someone else to do it, you would use the past tense, such as żeby zapiął.

Does foteliku just mean a small armchair here?

While fotelik is structurally the diminutive of fotel (armchair), it is the standard vocabulary word for a child's car seat or a high chair. Given the context of seatbelts (pasy), it translates directly to 'car seat'.

Why do we use the plural pasy when a car seat only has one seatbelt system?

In Polish, vehicle seatbelts are almost always referred to in the plural as pasy, even when talking about a single passenger's harness or belt. The singular pas is usually reserved for a belt you wear to hold up your trousers or a geographical strip of land.