I agree - stick to the facts.
I have spent a lot of time in EAP meetings over the past 8 years. A great book to read, btw, is Wrightlaw's book called "From Emotions to Advocacy." Don't talk about how you feel, don't try to make the superintendent feel like he has to take sides. It sounds as if it is safe to say, building on what someone else recommended, that you have had some concerns and these are echoed by others you work with who urged you to meet with the superintendent as they have done. If handled correctly, you can make this seem as if you're a team player.
Your idea here is to get to a win/win. Don't back the superintendent into a corner. Do make him feel that you are appealing to his knowledge and authority and problem solving abilities. Tell him straight up what your concerns are, using I messages. Don't accuse or blame the supervisor - esp. given that the superintendent is male and in a position of authority, so try to avoid making it seem that he is being pulled into a personal battle or a catfight. But an example is, "I don't have tenure, so I realise I'm putting a lot on the line here. I have learned a lot from SUPERVISOR, and I value our relationship, but I'm worried that I'm being set up to fail/to be fired." Laugh: "I don't think I have anything to lose at this point." Appeal to his authority. "I heard from others that you were the person to talk to about this. How can I approach this problem? How can we work together to solve this problem? I don't have any answers. I love my job, I've loved working with her, and I'm distressed that things are deteriorating." Stuff like that.
I"ve sat in meetings with assistant superintendents crying because that 3rd grade teacher who was singling my kid out was the only 3rd grade teacher she'd ever have... but that superintendent didn't care, and it made him uncomfortable, it made him want to get me out of the office and to stop crying. It didn't help my daughter, it didn't help us figure out goals (SMART goals!
SMART criteria - Wikipedia, the free encyclopedia ) to address how we could get her needs met.
Might help if you have given some thought, too, to what you want out of this meeting. Specific, measurable, attainable, relevant, timely ideas...
Not that you are telling him but that you can throw an idea out and say, hey, I thought about doing this but I'm not sure how it would work/if it would work/if it's appropriate. It's a way of getting the conversation started.
Another thing to ask, esp. if emotions start to run high, take a step back and say if you're getting emotional and apologise. Then go back a step and say, we talked about this. Let's look at it another way: if I did this, what would that look like? How do you see that working?
Those two questions are questions that don't get asked, a lot of times, oddly enough. And yet they are really good for refocusing onto the problem, instead of the emotions.
Sorry for the info dump. I've spent a lot of time on this stuff and I'm nowhere near "good" at it but I'm always learning...