Grinding noise when trying to start engine

My wife’s car is making a grinding noise when I try to start it. The lights and radio come on and the battery seems ok. Is it the starter?

2 possibilities come to mind. Bad battery or broken teeth on the flywheel. Does the motor turn over slowly, or not at all?

Most likely, it is the battery.
Merely being able to power the radio and even the lights does not mean that the battery still has the power to crank the engine. Another possibility is a battery that is still in decent shape, but because of loose or corroded battery connections, its full power is unattainable.

Model year of your Cavalier?
When was the battery last replaced?
What do the battery terminals look like? Do they appear to have corrosion on them?

Edited to add:
“Not at all.”

You need a new battery.
Most batteries are ready for replacement after ~5 years, or possibly sooner if the car is used mostly for local driving.

Not at all.

No corrosion. It’s an '89.

I had a similar issue a few years ago on a Focus, it turned out the be a bad a/c compressor. It has seized and caused the car not to turn over.

When was the battery last replaced?

Does the pitch of the grinding noise change after you try and start it? Kind of like grr grr zing?

I don’t believe it would make a grinding noise it the battery was low or dead. I’d rather believe that the teeth on the starter or the flywheel were bad.

Have you found the problem yet??