Learn Turkish: Müze pazartesi kapalı. - The museum is closed on Monday.

In Turkish, you don't need a preposition to say that something happens on a certain day. You just use the bare name of the day! Simply saying pazartesi in a sentence is enough to mean "on Monday."

Why isn't pazartesi capitalized like Monday is in English?

In Turkish, days of the week and months are written in lowercase unless they are at the beginning of a sentence or part of a specific, exact calendar date (like 15 May Pazartesi).

Where is the verb "is" in this sentence?

Turkish often leaves out the "to be" verb in simple, everyday statements in the present tense. Just putting the subject (müze) and the adjective (kapalı) together naturally means "The museum is closed."

Is there a trick to remembering the word pazartesi?

Yes, it's a combination of two words! Pazar means "Sunday" (and also "market"), and ertesi means "after" or "the following". So pazartesi literally means "the day after Sunday."