Hiring teaching assistants for an introductory physics class

After interviewing a few candidates for teaching assistant (TA) positions within the framework of our introductory experimental physics (classical mechanics and thermodynamics) class for freshmen this week, I have had some new thoughts on teaching and learning physics in higher education, especially with regard to TAs and their significance. In the following, I will discuss some of these thoughts.

• Get to know your potential TAs. I noticed that it is really helpful to interview future TAs for at least 10-15 minutes in person -- perhaps the term "interview" sounds a little too formal, it was more like a nice conversation. This allows for a better assessment of their skills and personality. Emails may not always give the right impression of people. In addition, a real conversation gives instructors a chance to understand the diverse backgrounds of TAs. Most likely, we will have TAs who are still B.Sc. (undergraduate) students themselves, whereas others are M.Sc. or even PhD (graduate) students. For some, it is the first time that they will be a TA, others have a vast experience in teaching already. Especially the latter may provide valuable input for the course. This diversity in their background will certainly be a great benefit for the class. For instance, young TAs may relate to freshmen more easily, since it is not too long ago that they have been freshmen themselves.
  
• Let your future TAs get to know you. Especially those without prior experience may have a lot of questions. Also, every instructor has different expectations, ideas and priorities for their class, so it is helpful for TAs to understand that. Do not just share your own expectations, but show your interest for their thoughts, motivation and suggestions.
  
• Plan regular meetings with your TAs during the semester, ideally once per week. Discuss about the current problem sheets and their solutions, the lecture, the discussion sessions, problems that students might be facing, general issues and other topics. Each tutorial or group of students led by different TAs may encounter different problems. Have an additional meeting with TAs before the semester begins. 
• Define clear rules in a syllabus-like document for the students (and the TAs). Convince TAs to follow these rules (e.g., regarding deadlines for handing in solutions to problem sheets as well as their grading), such that there are no significant differences in the standards applied in different groups by different TAs.
• Ask TAs to offer office hours for their students. Students may ask them questions which they do not dare to ask during the lecture or in the instructor's office hours. TAs may help them with the problem sheets, etc.
• Ask TAs for their feedback and ideas. This should be self-explanatory. I have made several notes during the interviews/conversations and thanked the future TAs for their input. For instance, inspired by one conversation with a candidate, we are considering to have students take a self-assessment test in mathematics during the first week of the semester. In the past, we noticed the freshmen's skills in math may be quite heterogeneous, so a self-assessment may constitute an ideal tool for students to understand their strengths and weaknesses. The results will also help us in the design of the class and problem sheets, etc. 
• Let people know that you are looking for TAs. This is obviously important at universities where instructors are struggling to hire a sufficient number of TAs. Ask your colleagues. Ask students in the elective class that you taught last semester. Post an announcement online or in the hallways of your institute. Ask your research group members (students) to ask their friends.
  
• Try to hire as many TAs as possible and reduce the size of the groups of students attending the TA discussion sessions. From my personal experience, groups of 8 to 12 students are ideal in experimental physics tutorials.
  
• Provide a sufficient amount of materials (such as solutions to exercises) for the TAs. For instance, they can take a look at the solutions to problem sheets prior to the weekly meeting and then you can discuss potential issues or alternative solutions. 
• Communication is important. Honesty as well. It is better to tell students that you do not know the answer to one of their questions as a TA and you will think about it or look it up and then discuss it next week (or in a subsequent email), instead of not giving a response at all or even give a wrong answer. Eventually, students will appreciate it.