This picture of the Demo School timetable should make some concepts clearer.
1. This week is greyed out because it is set to 'inactive' in the 'Term dates' tab.
2. Lunch break - this is set in 'Teaching times'.
3. Ella has two lessons at the same time only 3 weeks apart. This is OK because the default Rotation is set to 3, but closer than that is not allowed.
4. In the 'Pupils' tab Dave's rotation is set to '1' (in effect, off). This overrides the default rotation so he can come at the same time on consecutive weeks.
5. Brian also has consecutive lessons because these times are set under 'Rules', again overriding the default.
6. These two lessons clash slightly but only by 5 minutes - this is set under 'Rotation margin' overlap. A gap can also be set to keep lessons apart.
7. Carly has the day off today - also set under 'Rules'.
If you have a list of pupils in a spreadsheet or in a csv file you can paste the data directly into the pupil list. The data columns (fields) should be in the order: christian name, surname, form, and lesson length. Here's a view of a typical Excel list showing the copied area:
Then click in the import area, paste (Ctrl V) and click Import. There is a reason for this awkward two-step method to do with browser security (the website can't import directly from the clipboard).
V4 uses a random algorithm which doesn't guarantee to find the optimum table in terms of fewest gaps. Sometimes it won't work at all. If this happens the first thing to try is to click Update a couple of times in case you were just unlucky! Then try reducing the rotation period, or allowing slight overlaps. If it still doesn't work, please save the school to disk and send it to me by email and I'll try to work out what's happening.
Very occasionally a lesson might jump an hour when you try to move it. I know it's to do with time zones but haven't got to the bottom of it yet.