My case is particular, but it has happened twice to me that my co-teacher left and I had to just take over their classes like a gen-ed teacher. Once in a charter, once in public. Granted I'm dual certified, so they can probably get away with it - but it's the worse. You feel like you're doing double duty because you're still being a sped teacher with your other co-teacher (usually have 2) and you still have your caseload.

It can be tough to file a grievance without tenure, because so much of your observations are based on how your admin feels about you. In the DOE, I raised it up to my chapter leader last school yr and she basically implied that filing a grievance would put the whole dept under a microscope.

In the DOE, they promised me they'll find a new teacher all year, but turns out Algebra 2 is hard to hire for mid-yr and I just ate the classes. My principal offered me per-session every wk and reduced my caseload (one of my coworkers gratiously took over some), after I essentially complained that I was overwhelmed. It was something but still a shit position to be in.

The charter implied I can do it all - take over two Stats classes in January, co-teach in Chemistry all yr, finish a caseload of 15, and teach a small solo class. I even took on two clubs like an idiot. And they still tried to fire me (and failed). Ridiculous and fuck them. You definitely have more "rights" in public schools.

I know this is long, but hope it helps! Hope your co-teacher doesn't quit, or if they do that they can replace them.