Yes
Cover setting up the grinder, how to operate it properly including guard adjustment
On off switches, use of side handles
Selection of appropriate abrasive wheels for the applications ,e.g cutting, grinding
Identification of appropriate abrasive wheels ,.e.g speeds, application, dimensions, rotation direction, age, etc
Go over the operator manual with them.
Go over the hazards, noise, dust, vibration, electricity, slips, trips, flying debris, ejected material etc.
Go over proper handling e.g. use of side handles, no one handed use of grinders, direction of cutting
Use of appropriate PPE, full face protection to EN166B or A is better than just goggles (a disc shatters and its not just your eyes at risk). Hearingproteciton, gloves, FR clothing.
Watch videos, plenty available showing good practice.
Go over other risks, those including the use of the equipment and whatever else could be a haxard nearby, such as flammable materials ignited by sparks,
go over the control measures required for safe use.
Ask them questions (written) to ensure they undersatand the content.
Monitor use of the equipment and then when happy, sign them off.
I have probably missed a few things, but you get the idea.
Be in no doubt these can be lethal bits of kit in the wrong hands.
Good luck