Our day is based on times rather than periods

Period Timings - an Overview:
Most school days are arranged around an agreed number of 'periods'.
However, if your school day does not fit neatly into periods, and uses different length lessons for different subjects, etc ... then you can still timetable this in TimeTabler. Many schools use TimeTabler this way, especially outside the UK.

Planning - simple case:
The first thing to consider is: how easy this will be will depend on the difference / variety in period lengths.  Your timetable will still be based on a number of ‘periods’ in each day, so if your lesson lengths are easy multiples of each other (eg: each lesson is either 30 minutes, or 1 hour) then you can simply say that a period is 30 minutes, and then a 30 minute lesson is a “S”ingle, while a 1 hour lesson is a “D”ouble.
Singles and Doubles are very easy to enter in TimeTabler - you just enter S or D for each lesson.

A more complicated case:
If your times are more varied than that, then you might need to find the “highest common factor” of all your lesson lengths, and base your periods on that.   But in such as case, you should first review whether such a variety of period lengths is really necessary … as it does make timetabling more difficult, which in turn may affect the quality of your final timetable.  And of course, a poorer quality timetable has a knock-on effect on staff and on students.
So taking an extreme case, if some of your lesson were 15 mins, some 20 mins, some 30 mins, some 45 mins, etc ... then your “highest common factor” would be 5 minutes.  So you would make your periods 5 minutes long, and a 15-minute lesson would be entered as a "T"riple-period lesson.
Such a timetable is sometimes called a 'Grid' or a 'Modular' or a 'Granular' timetable.

Your MIS / SIS / Admin System:
The final factor to consider is how your MIS/Admin System would like/expect the final timetable to look, when it imports it.  So before starting the timetable, you need to check: is your MIS happy to accept 30-minute periods (or 5-minute periods, if that is what you have chosen) ?   If your MIS supplier wishes to discuss this with us, just let us know.

See also the article on Senior & Junior timetables - timings which discusses different start/end times for different years in your school.

If you have any questions about any aspect of this, please ask.