As a TA, you should expect to do the following:

Design and prepare lessons and activities

Lead class discussions, activities, etc.

Give students feedback on their work- both written and verbal feedback

Meet with your leadership teacher on a regular basis

Attend biweekly after-dinner meetings with all TAs

Serve as a role model and a mentor to the younger students, both in and out of class

Attend every class meeting (most TAs have 2 class meetings per week, but some will have 4)

undergo and model an honest self-evaluative process: seek out feedback, utilize constructive criticism

teach the class if your teacher cannot be there for some reason