stay flexible
These are some general guidelines [the Biggio TA Handbook is coming in Fall 2009]. In each discipline, the conduct of recitation sections (also known as 'discussion' sections) will be different as the instructional goals will be different. In some science and math courses, these sections will have a heavy dose of problem solving as part of the activities. The USC TA Wiki website created by TAs offers some tips for the weekly discussion section. They offer tips on how to (i) create, plan and deliver effective and creative discussion sections (ii) feel more comfortable and confident leading a discussion section (iii) identify, avoid and manage common challenges that arise during discussion sections. Here is a short excerpt:
Preparing for Weekly Discussions : You may find yourself one of few Teaching Assistants in a course. For larger classes, you may find the course has a larger number of Teaching Assistants with a lead/head TA. Each professor has his/her own style and methods for managing Teaching Assistants throughout the semester, but it's up to each individual TA to prepare for weekly discussion meetings.
Before you meet your students, here are some things to keep in mind: Do your homework! While you may have led a discussion section for the same class last semester, it's still important to prepare for each new semester and group of students.
Make lesson plans - but be flexible. Think about "What do I want my students to learn today?" Estimate how much time each part of your lesson will take - but be ready to be flexible in case you have time left over or in case you run out of time before you finish everything you'd planned.
Ask for advice: Ask other TA's what they have planned for that week's discussion. Check with the professor to make sure you're focusing on what he/she feels is most important for students to understand.