Hi there, @catherine-wissi ...
I did a bit of searching here in the Community for the documentation on discussion checkpoints, and here is what I found:
I'm not sure if you are a Canvas administrator at your school, but it looks like the Canvas admin would need to contact their assigned CSM (Customer Success Manager) to get this enabled in your Canvas environment.
Once enabled, within your school's Canvas admin pages, it would be listed as a Feature Option like this:

There are essentially four "states" that this Feature Option has:
- Enabled and Locked - Discussion Checkpoints are turned on for all courses in the account with no option to turn it off at the course level.
- Enabled and not Locked - Discussion Checkpoints are turned on for all courses in the account with the option for instructors to turn it off at the course level.
- Disabled and not Locked - Discussion Checkpoints are turned off for all courses in the account with the option for instructors to turn it on at the course level.
- Disabled and Locked - Discussion Checkpoints are turned off for all courses in the account with no option to turn it on at the course level.
Hopefully that helps to clarify things for you. Sing out if you have any other questions about this...thanks!