A few students requesting to cancel lectures due to their personal reasons. What should I do? I give lectures to postgraduate students. The number of students in this batch is very low (&lt; 20). The lectures are foundation lectures for the course. We are only into the basics of the course. 

A few (maybe 4) students of this batch are requesting to cancel two lectures as they won't be available for personal reasons. In fact, they are going to attend a workshop. In my university, attending workshops that are not fully recommended by the department is considered 'personal interest'. 

One option is to ignore their request and ask them to study the topics covered during the lectures or with the help of students present during the lectures. If they could study these topics themselves or with friends, they wouldn't have requested me to cancel these lectures. 

What should I do in this case?

I could ask this question to my head of the department, but, I don't know how this will turn out for students. They should not feel that they were not allowed by the head to attend this workshop.

I do understand that there will be variations of opinions on my question as per the different academic rules of universities but I still want some insights from experienced academicians.
If you do this for a minority, then you will have to do it every time a few students have some excuse.

I suggest that you don’t consider this and make it clear that if they miss lectures then it is up to them to catch up on material.

Providing double or triple repeats of lectures due to a few absences, especially if unpaid, is not a good use of your time.

Some students will want to rationalize their choices and make sure which they attend - some workshops can be valuable. If you think one workshop is very worthwhile then you could consider re-scheduling for all, but that depends on your schedule, and yes, I have done this for similar reasons involving the majority.

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I always provide the material used in class - notes &amp; worked example on Moodle as well as further practice problems (some 10 to 20 for each topic with solutions) for those who attend as well as those who do not.