Questions & Answers about På fredagar har de ofta ett litet prov i skolan.
Swedish uses the plural of the weekday without an article to talk about habitual or repeated events:
- På fredagar = On Fridays (every Friday / most Fridays)
- På fredag = On Friday (this coming Friday / one specific Friday)
So "På fredagar har de ofta ett litet prov i skolan." means this happens regularly on Fridays, not just once.
For regular, repeated events, Swedish normally uses the bare plural of time words:
- på fredagar – on Fridays
- på måndagar – on Mondays
- på kvällar – in the evenings
Adding an article would sound too specific, like talking about some particular set of Fridays. The natural, general way is just "på fredagar" with no article.