Schedule. This could be tricky first of all because of pronunciation, because some people say /šedjúl/ whereas others say /skedjúl/. One explanation may be that the former is British and the latter American English pronunciation, but I'm not sure. It could be that the people who say /šedjúl/ are influenced by German, whereas the /skedjúl/ pronouncers want to standardize it with "school" and "scheme" /skím/.

Either way, the best thing is to accept both pronunciations, choose one for your own use and then be consistent. The other potential trickiness is the number of meanings the word "schedule" can have. It can mean a plan, a program, a timetable, an itinerary, a list, an official document (for example an attachment to a contract).