How are TA positions typically filled?

[Wackstrom]

Noob question alert, but as a new grad student, I'm getting antsy about finding a TA position next year since the chance of funding is very low. Are TA positions typically offered by professors directly to students they already have in mind? Or are they posted as an open listing for anyone to apply? And is it proper for students to directly contact professors prior to the following term to see if they can TA for a specific class?

[fuzzylogician]

This depends on the specific department. Why don't you contact the department admin and/or DGS to ask? 

In my department, for example, students submit their preferences for which class they want to TA. Professors can express a preference if more than one student wants to TA their class. Sometimes they can also 'nominate' someone. But there's no shortage of positions in my department, so it's probably different from yours. Ask around. 

[TakeruK]

Like fuzzy said, it's best to ask the department. But I found that there are two general scenarios:

1. There's no shortage of positions and the main goal of the TA assignment process is to make assignments to optimize interests/productivity/scheduling/preferences.

2. There are more students that need TAships than there are positions, so TAships are a resource (since money for paying TAs comes from the dept/school, rather than the advisor). Generally, there will be some procedure that determines priority of TA assignment. This might be encoded in a union contract, University policies, offers, etc. It might mean that students are guaranteed X years of TAship based on the offer letter, or students within the dept having priority over those outside, or students without fellowships having priority etc. If this step results in enough TA positions for the highest priority students, then it might go like scenario 1. Otherwise, there may be another step where qualification is assessed and TA assignments made based on qualification. This could involve a small committee, a TA coordinator, or the prof of the course deciding who is best suited for their course.

My PhD school worked like scenario 1 and the prof in charge of appointing TAs asks both students and faculty who they would like to TA for/have as a TA. Generally, students talk to the profs they want to TA for ahead of time, since if both TA and prof pick each other, it will almost always go through. However, this happens on an unspecified day and the email only gives you like 24-48 hours to respond so we always tell first years to think about this by April/May so that they can get preferred assignments for their 2nd year (first year students do not TA, they all get fellowships). Just another example how it's important to ask around and find out how things work, since this is not publicized anywhere in our dept.

[DGrayson]

It also depends on if you are a Masters vs Ph.D student. At my University, teaching is guaranteed for Ph.D students, while the Masters students basically have to fight for whatever's left. Check to see if there is a database where different departments can publish open positions. If not, I would email the program admin in the departments where you have a strong enough background to teach and let them know of your interest and provide a copy of your CV. 

[pinoysoc]

Teaching positions are often filled through the basis of need. GA-ships are usually TA or RA. Those who get GTA-ships are TA's for introductory classes. It's also dependent on skill level. If you're further in the program, you usually get to teach your own class (which is the case for most doctoral students finishing up). Or if you're in the middle (i.e. second/third-year) you might be the lab instructor/assistant for classes that have a lab component to them. Of course, this is from a social science (sociology) perspective; and it will vary as well based on the academic field you're in.

[ThousandsHardships]

As people have said, it varies a lot from department to department. In most cases, you don't have to specifically apply to be considered for a TA'ship within your own department. They automatically consider you a candidate and the most they do is check in with you to make sure you're still interested and what specifically you're interested in teaching. In filling TA positions, first priority usually goes to PhD students with no outside funding, then master's students with no outside funding. They also consider students from outside programs whose research is closely affiliated with the program or whose research advisers are within the program. If they fill up all the slots available with these students, then that's it. If not, they will open up applications for unaffiliated graduate students and sometimes even advanced undergrads who've taken and aced the class in the past.

[lemma]

Get in early if you can! At my university, for regulatory reasons, TA positions have to be filled months before semester. This has meant that PhD students in my cohort missed out on being able to teach in their first semester. 

I would flag your interest in teaching to your supervisor or the PhD coordinator and go from there. I flagged it to my supervisor who it turned out was looking for TAs for his class - I got lucky.