Teaching assistants

[doc700]

I am a 4th year professor and am teaching an intro STEM course for freshman majors.  I have two teaching assistants who are assigned to support the course.  The TAs teach sections to support the lecture and grade.  I have taught this course twice in the past and things have been very smooth with the TAs.  This year I am having a serious issue with one of them.

The TAs are given (by me) problems to work out during section.  These problems were written for a prior iteration of the course but are in general excellent problems that integrate the concepts from class with advanced problem solving skills.  The problems are also well aligned with the homework and exam problems.  In the past the TAs have had no issue working out the problems in section and the students have enjoyed seeing homework like problems.  The students have given high reviews to their section leaders and section overall in the end of course evaluations.

This semester my TA refuses to help show the students how to do the problems.  She gives them the problem in a group and then tells them they are lazy if they can't figure out how to solve it.  These problems are non-trivial and I've tried explaining that while the students should be given time to work, the purpose of section is for her to model problem solving strategies.  Coming from lecture, they still need support putting everything together to solve these problems (but should be getting modeling so they can work on the homework of similar difficulty).  I've trying highlighting key steps and points with the TA but shes defiant in her approach.

Finally the mid-term section evaluations came back and they were extremely negative for that TA (but strong for the other TA).  The TA decided to try my approach and asked to model a section for me.  I realized the real issue was the TA had serious misconceptions about the material and made several errors in solving the problem.  This was even when given a decent solution to work off a week in advance.  The worst part was when I asked her small questions she was confident and direct in her answer while giving completely incorrect information, rather than admitting what she didn't know.

Since the term started, I've had about 2/3rds of the students in that section reach out to me, either in tears since they can't do the problems or aren't learning or that they want to change to the other section leader.  The other section is quite full so this is not an option to move a significant number of students there.  I do seem to have somewhat enforced the need to help students solve problems, but the TA not understanding the material seems like a fundamental issue. I don't want to force students to go to a section where they get incorrect information and explanations but even after spending 1 hour rehearsing a section with the TA the reviews were terrible from that section so I don't know what else to do. 

Any ideas?

[the_geneticist]

You are correct that having the TA not understand the material is a serious concern.  Having the students work in groups is a good strategy, but not if the TA is unhelpful.
You could require the TA to carefully work through the problem set with you to create a problem solving guide (DO NOT give her the answers ahead of time).
At this point, you're going to have to just make it to the end of the course.  Can't fire the TA or require the other TA to teach all of the sections.  And I'd make sure that this particular graduate student is not a TA for this class again unless you see some pretty dramatic improvement.

[doc700]

I should add I agree the students should be working in groups.  They shouldn't be given a complex problem and told to sink or swim for 60 minutes/berated when their group can't get the answer unsupported 60 minutes later.  Why go to section at all at that point?  If you know how to do it, you don't need to be there.  If you don't know how to do it, you aren't going to learn anything.  I think the ideal section should toggle back and forth between student work and instruction, with emphasize on talking through the process of how to approach the problems rather than "just" solving the specific problem.  But there should be some leadership from the front.

The TA does have all the problems for the term.  This is a standard intro course and I got a packet of section problems from the prior professor.  There are a lot of problems in the packet and I will tell them which ones to do first etc but she does have access to the solutions unless I start writing new problems.

[dismalist]

Can you terminate the bad TA for cause and use the money saved to have the good TA work twice as much?

[doc700]

The good TA is already working 20 hours per week which is the max assignment since the remainder of the time should be for her own research projects.  I could try to fire the bad TA but am not sure half way through the term who I could get.

[zuzu_]

Can someone get video of the good TA modeling the problems? And then post the video online for all students to review?