If the previous (or more generally, some previous) laboratory had its extension to the start of this one, then you should announce to the students that they should put their names and machine name on the marking queue on the white board if they are ready to have their work from the previous session marked. The demonstrators can then mark those in a random order - students who are trying to ``steal'' a little extra time may put their name near the end of the queue in the hope it will be processed from start to end.
When you take attendance, you will see a little less than sign (`
') to the
left of the names of those students who did not complete the previous work by
its deadline. It's a good idea to ask such students whether they have now
completed the previous work. You're not going to check, simply ask; and there
is a small risk that some will lie to you. But the majority will be honest,
and it will reinforce the principle that extended deadlines are at the
start of laboratories, even though the work may not get marked until
near the end of the laboratory. Some students, especially in the early
laboratories, will tell you that they have not completed. You can then discuss
with them why not. Some, especially first years, will say they were confused
by the deadline system, some will say they're having unforseen problems with
it, and some will tell you that they've been ill or whatever.
If they have special circumstances, then deal with that as described in §15. If they haven't then use your discretion. For example, in the early laboratories, especially for first years, you may give them a little more time ``this once'': e.g. perhaps as much as an extra hour from the start of the laboratory. Or you may need to tell them to stop work on it now, cut their losses, have it marked as it is, and get on with the next exercise. Or it might be obvious that they have done very little of the work, so they need to be told it is now late. See below about reducing student demoralization due to late flags.
While asking these questions, you may find it helpful to write a little tick inside the less than sign, for those who claim they have completed, a cross for those you decided are now late, and a question mark for those you've given a bit more time to. This is purely for your use - the team of data-entry demonstrators will ignore these markings when the sheet is processed for data entry. It will help you remember what you've agreed, so that at the end of the laboratory you can cross check it with the corresponding sheet for the work which had the extended deadline. In particular, you can ensure there is a cross in column 4 (``completed by extended deadline'') for those students you have told are late.