I can certainly speak to this from my own experiences. Since I've mainly taught chemistry, my experience has largely been teaching labs. UMSL gave me the opportunity to throw in discussion sessions as well. Typically, the lead-up to any of this at the start of the semester was anything from a day to a week of seminars about being a TA. Some of it plain common sense and some of it just policy. I found much of it to be unhelpful, but like I said, a lot of it is common sense.
I saw a lot of foreign grad students sent to lead classes or discussion groups who had very poor english. That should never happen. You are handicapping their students by giving them a second hurdle to overcome (aside from understanding the material).
If I had to give my own thoughts to improving the situation for science TAs, this is what I might say:
- Public speaking classes
- Allow time to test the labs
The easy solution to this would be to bank time for the TAs to all do each experiment before teaching it. This way they know the equipment, they know the reagents, and they know what each stage of the experiment looks like.
- Give the TAs real authority
In every case, I really had no recourse. I'm not allowed to deduct points at any stage for behavioral problems. I was only allowed to report to the professor about the problem and let them handle it. It usually meant a warning to start, then an "official" warning in the form of a hearing with a disciplinary panel. Too much run around for a very slow pay off.
The point is, the power lies in the hands of either the students or the professor. The TAs are simply middle men with no ability to keep students in line short of having campus police haul a disruptive trouble maker out of class. That's not helpful to anyone.
- Give them a chance to lecture
I realize that's not a feasible option for courses with 300 students and 20 TAs, but the option could at least be offered to those TAs. Nobody learns to drive by first pulling onto the interstate during rush hour or going into a downtown metropolis. Why should teaching be any different?