Questions & Answers about W sobotę dzieci grają w koszykówkę na boisku przy szkole.
The preposition w has different meanings and takes different cases:
- w + accusative = on (a day), into
- w + locative = in (inside)
For days of the week meaning “on [day]”, Polish uses w + accusative:
- sobota (nominative, base form)
- w sobotę (accusative) = on Saturday
w sobota is wrong because sobota is nominative, not accusative.
w soboty is accusative plural and usually means “on Saturdays (in general, repeatedly)”, e.g.:
- W soboty dzieci grają w koszykówkę. – On Saturdays the children play basketball (every Saturday).
In your sentence it’s w sobotę (singular), so it sounds like one specific Saturday or a particular repeated plan understood from context.