Yes, as the course creator you can decide whether a sequence of lectures is optional or mandatory.
By default the sequence is optional and the learner is free to attend the different lectures of a course in any order. To make the sequence mandatory, check that option in the course's lectures list.
To make the sequence mandatory, you’ll need to check that option in the course's lectures list. Here is how:
Please, find the needed course and click Manage Course. Then click on Edit Lectures button, or simply go to Content > Edit Lectures.
Once in the lectures list, adjust the setting to your liking. You can also decide whether to allow the users to fast forward the videos and to download the documents.
You can change the order of your lectures with drag & drop.
If an exam has to be taken after a certain lecture then this exam becomes part of the navigation.