So first a question: why would you want to disable a lesson? Well, since there's no way to remove a lesson associated with a student or a group (you can only assign a new lesson and replace it), disabling a lesson is useful if a student is going on a break, or will be unable to use Tonic Tutor for any period of time. Rather than having a bunch of unfinished lessons, you can put everything on hold until they're ready to resume their studies. You can disable an individual student lesson on a student's Student Options page (which we covered in the Student Options tutorial). In the screenshot, the Lesson Switch for William is ON. If I turned it off, his lesson would no longer show up when he signed into his account (until I flipped it back on).
There's also a way to turn off ALL of the lessons for your students in one easy step. This is useful for summer if you want to hit the pause button. You can turn off lessons globally on the Options>Settings>Teacher Settings page. If this setting is set to turn off all student lesson it will override the individual student lesson switch.
View the next tutorial: What are Lesson Years?