Hi @Icka ,
Find the activation code in:
Mobile Device > Management > Activation Lock Bypass Code

Note: Supervised: Yes – If the device is not supervised, the Activation Lock Bypass Code will not be available.

For devices locked with Find My, first, restore the device. In the password section, copy and paste the activation code (ensure the device is connected to the internet).

Here are some references you can read before proceeding with the restore process.
https://learn.jamf.com/en-US/bundle/jamf-now-documentation/page/Using_Activation_Lock_Bypass.html
https://it-training.apple.com/tutorials/deployment/dm265/
Hopefully, this helps
@Icka In addition to the option described by @agungsujiwo if the devices are in your Apple School Manager account you should see the Activation Lock status when viewing the device record, and clicking the ... button in the upper-right corner of the ASM window will give you the option to turn off Activation Lock if it is enabled.
I have seen that in the Apple School Manager before. I was reluctant to turn it off because I was not sure if I would be able to Activate it again in ASM. Meaning the activation lock would stay off.
So for example. If I Turn Off The Activation Lock, get it all set up for another teacher, and later that teacher logs in with their Apple ID, and Find My turned on, will it show up in ASM as being On again?
I have seen that in the Apple School Manager before. I was reluctant to turn it off because I was not sure if I would be able to Activate it again in ASM. Meaning the activation lock would stay off.
So for example. If I Turn Off The Activation Lock, get it all set up for another teacher, and later that teacher logs in with their Apple ID, and Find My turned on, will it show up in ASM as being On again?
You can disable Activation Lock in prestage enrollments:

Then unless you take steps to enable it users can't enable Activation Lock.
@agungsujiwo posted a good article about Using Activation Lock Bypass. If the device is in Apple School Manager it should be easy to disable activation lock on any Apple devices you have using that. For everything else use Activation Lock Bypass.
You can learn more about Leveraging Apple's Activation Lock Feature with Jamf Pro as well.
I have seen that in the Apple School Manager before. I was reluctant to turn it off because I was not sure if I would be able to Activate it again in ASM. Meaning the activation lock would stay off.
So for example. If I Turn Off The Activation Lock, get it all set up for another teacher, and later that teacher logs in with their Apple ID, and Find My turned on, will it show up in ASM as being On again?
Not sure if the other reply fully answered this question for you, but yes. It can be re-Activation Locked later by either the same user or another user. This is similar to clearing the passcode on a mobile device. It's persitent, but not permanent. The passcode remains cleared indefinitely. However, it can be turned back on by the user. Activation Lock, in this context, functions that way.