Many graduate students are employed by the colleges or departments to teach undergrads. As well as being a handy source of extra money, this can be good experience for anyone interested in an academic career as well as reminding you that there's more to your subject area than your own research speciality.
The main types of teaching job available are:
- Supervisions - teaching small groups of one to three undergrads in one hour blocks. These are usually arranged by the colleges. You may be asked to commit for a term or a whole year. Although the pay is quoted as over £20 per hour, remember that you have to teach for this hour, and additionally prepare and mark the students' work, so each supervision will usually take up well over an hour of your time.
- Practical classes - run especially by science departments, these often have several research students as demonstrators, often with an academic member of staff in overall charge, and can be one afternoon or all day. Again, you may be expected to agree to a whole term's work. Practical classes demonstrators are more likely to be paid for the amount of time they are actually required to work, although rates are lower to reflect this.
Note that most funding bodies restrict the amount of work you may do, and this includes teaching.
Each Michaelmas term, the University runs a seminar for new supervisors. It isn't obligatory to go, but can help you to learn what is expected from supervisors. You can also ask an experienced supervisor if you can sit in on a supervision to observe.