Learn Turkish: Geçen hafta ormanda yürüdük. - We walked in the forest last week.

The verb root is yürü- (walk). First, we add the past tense suffix -dü (matching the 'ü' because of 4-way vowel harmony). Then, we add the personal suffix for 'we', which in the past tense is just -k. So, yürü- + -dü- + -k = we walked.

Wait, isn't the suffix for 'we' usually -uz like in yürüyoruz? Why is it -k here?

Great catch! You are thinking of the present continuous tense, where 'we' uses endings like -uz (as in yürüyoruz). However, the witnessed past tense has its own special set of personal suffixes. In this past tense group, the suffix for 'we' is always just -k.

Does geçen exactly mean 'last'?

Not exactly! Geçen comes from the verb geçmek (to pass). It literally means 'passing' or 'that which passed'. So to say 'last week', Turkish says geçen hafta (the passing week).

Why isn't the word biz (we) in this sentence?

Turkish often drops subject pronouns like ben (I) or biz (we) because the ending on the verb already tells you who is acting. The -k at the end of yürüdük clearly means 'we', so adding biz at the beginning is optional and usually left out unless you want to add emphasis.