The -ken converb
-ken is the Turkish 'while'. It attaches mainly to the aorist (the -er/-ar/-ır/-ir form) of a verb to mean 'while V-ing'. Yürürken telefon ettim. = I called while walking. It also attaches to nouns and adjectives to mean 'when (someone) is/was X' or 'as a X': çocukken = when (someone was) a child / as a child. The suffix itself is -ken and never harmonizes — same form, every time.
Forming -ken on a verb: the aorist + ken
Take the verb's aorist (the wide-present tense — see lesson on aorist for full forms): yürür (he walks), gelir (he comes), bakar (he looks). Drop nothing — just add -ken. yürürken = while walking. gelirken = while coming. bakarken = while looking. yaparken = while doing. giderken = while going. The aorist marker stays attached; -ken sits on top. Most learners just memorize this combo as 'aorist stem + ken'.
-ken with progressive (-iyor)
You can also attach -ken to the progressive: -iyorken. Çalışıyorken telefon çaldı. = The phone rang while I was working. This is more emphatically 'in the middle of V-ing' than the aorist version. Both çalışırken and çalışıyorken are correct; -iyorken highlights the action was specifically in progress at that moment. In everyday speech the aorist version is more common.
-ken on nouns and adjectives
-ken also attaches directly to nouns and adjectives — no aorist needed — to mean 'when/while [is/was] X' or 'as a X'. çocukken = when (someone was) a child. öğrenciyken = when/as a student (buffer -y- after the vowel). küçükken = when (someone was) little. gençken = when young. The implicit subject comes from context, usually the main clause. Çocukken İstanbul'da yaşadık. = When we were children, we lived in Istanbul.
Subjects can be the same OR different
Like -ince, -ken doesn't require same-subject. Default reading is same-subject as the main clause: Yürürken telefon ettim = I called while I walked. To make it different-subject, supply an explicit pronoun or noun: Sen uyurken ben kitap okudum. = While you were sleeping, I read a book. Two subjects, no problem.
-ken vs -erek
Both can translate as 'while V-ing', but they're different. -erek describes manner — the same person doing the two things at once, often as means. Müzik dinleyerek çalışıyorum. = I'm working by way of listening to music / I'm working with music on. -ken describes a time frame — 'during the time that X is happening, Y happens'. Müzik dinlerken telefon çaldı. = While I was listening to music, the phone rang. Different subjects/events can use -ken; -erek sticks to one subject doing two things.
Negative is unusual — use bir şey yapmazken sparingly
The negative aorist + -ken (yapmazken, gelmezken) exists but is fairly literary. In speech, you'd typically rephrase: 'when not V-ing' becomes 'when X wasn't V-ing' with a different structure. For now, focus on the affirmative — that covers 95% of usage.
