I apologise. That's the academic in me; explaining everything in such a way as you leave knowing less than when you arrived.
What I mean is, there is no trial period. Instead, we are thrown in the deep end.
However, this will not be a detriment to the university, as if it turns out we are unsuited to the job, they have not actually lost any money, as we are only payed per tutorial, rather than as a lump-sum.