Learn Turkish: Koordinatör o çizelgeyi iptal ediverdi. - The coordinator suddenly canceled that schedule.

The suffix -ivermek is added to verbs to show that an action was done suddenly, quickly, or without much thought or effort. Here, it changes the standard past tense 'canceled' into 'suddenly canceled' or 'just went ahead and canceled'.

Why does iptal etmek change to iptal ediverdi with a d instead of a t?

This is a standard consonant mutation. The verb root is et-. When you add a suffix that starts with a vowel—like the -i in -ivermek—the hard consonant t softens to a d, giving us ediverdi.

Why do we need the -yi ending on çizelgeyi?

Çizelge (schedule or chart) is the direct object of the verb. Because it is a specific schedule being acted upon—indicated by the demonstrative word o (that)—it requires the definite accusative case. Since çizelge ends in a vowel, it takes the buffer -y- plus the suffix -i.

Is çizelge the only word for 'schedule', or could I use program?

You will often hear program for a schedule, plan, or itinerary. Çizelge is a bit more specific; it usually implies something visually drawn up in a chart, grid, or spreadsheet format, such as a shift roster or a timetable.