Usually, there is one native English teacher per school and assigned to them is almost always one Korean co-teacher, who should be an English teacher (a bit of a no-brainer, one would think). The relationship between the two is often a bit of an issue for foreign teachers working in Korea as it can be a recipe for disaster. Generally speaking, it seems like the younger the Korean co-teacher the better as they are less likely to get in the way of the Native teacher's classes and maybe even genuinely work together.
At orientation and in online training, quite a pleasant, pretty picture will be painted of this working relationship; you plan together, you discuss problems together, you teach the lessons together, and your co-teacher may even sort out some things outside of the school for you. The reality of the situation, however, is frequently very different.
First, from my own experience and what I can gather from others, you will be fairly lucky if your Korean co-teacher can speak English to anywhere near a respectable level. Then you will very fortunate to have a co-teacher that has any time that can be spared for you to discuss classes, students, problems, plan, etc. And finally, you will be exceptionally lucky if they actually help you at all in class.
Perhaps I am being a little bitter about this situation because my school is so astronomically terrible in this department. I have worked at a High school in Jeollanamdo now for about 2 years. In all that time, I have had 8 different co-teachers; only one was an English teacher and she was only in half of my classes for half a term/semester (she was actually extremely helpful as well). I had one other teacher who could speak English, who was actually a music teacher. The other six included; a maths teacher, two Japanese teachers, an old Korean teacher who was dying of cancer and so was put into my class (I can only imagine the reason was to let him sleep, because that is all he did), a geography teacher, and most recently the school nurse. All of these teachers could not speak a word of English, indeed my meagre knowledge of Korean was far superior to their English, which was non-existent.
Actually, I didn't mind any of this. I planned my own lessons and completely controlled all of my classes. The co-teachers would turn up sometimes and at other times not show, but if they did show they would simply read a book or get some marking done at the back of the classroom. Only with my most recent of co-teachers have I had problems, the school nurse.
This woman is about 3 feet tall and pretty weak in the discipline department - no surprise really as she is not even a teacher. However, this did not stop her from trying to discipline students in my classes, often when they were doing exactly what I wanted them to do, i.e. be enthusiastic about the class and speak English. She began telling them to be quiet more and more.
Rarely do I trouble my school about anything, I sort out all problems myself, both in and out of the classroom. Sometimes, however, I need a document from the school, to know my vacation dates, or scheduling information. Whenever I need this kind of thing, I usually have to ask them 5 or 6 times or they are unbelievably slow in getting things done. Even extremely simple matters that would take as little as a couple of minutes to sort out, often take weeks. It can frustrate the hell out of me. On the subject of my co-teacher, though, I was pretty keen on sorting things out fast, as she was ruining my lessons.
I complained, and when I got the usual nonsense and delaying tactics, I said I would write something down and ask my wife to translate. I said it was my own fault that I hadn't let her know what I expected of her from class number one. In a bit of a panic, the head of the English department (who sits next to me) pleaded with me not to and phoned another English teacher to try and rectify things (who works in the floor above me). He then called back and told the head of English to tell me to wait until next week. I simply said, "there is no time like the present, why not now? If you don't sort it, I will." I didn't want another ruined lesson and the impression to the students that I wasn't in charge, I was losing their respect with every class this was continuing in.
Panicked again, she called back to the man on the floor above, who then called to the vice-principal (who sits about 4 metres away from me and the head of English), who then called the principal (sits in the next room) and they eventually had a word with the school nurse about the issue.
To my school's credit, although I feel they don't place too much importance on my classes, I do think they trust my judgement and my teaching ability. Despite all the bureaucracy - and the fact that they gave me a school nurse as a co-teacher in the first place - they fully supported me and agreed that I should take full control of the class and that my co-teacher should not interfere.
This is just my story about troubles with co-teachers, but I have heard countless more. From my experience with the one co-teacher that could speak English and how we worked together effectively, it is clear to me that when there is a good working relationship between the the Native and Korean English teachers it is of great benefit to the students. I found that a good Korean co-teacher can especially help the low-level students, which are often the hardest to motivate because of their difficulty in accessing the lesson when it is solely done in English by the native teacher.
It does make me wonder about the whole NET set-up in Korea sometimes and their bizarre system for educating students in English. There is just no seriousness, responsibility, or care taken with NET's. You'd think that because the government spend so much money on us, they would make sure of our efficacy and put a little responsibility on us to get results. Instead they allocate most of us one lesson a week with 30+ students, no assessment for students taking our classes, and it seems little regard for making sure we all get adequate assistance from co-teachers in our schools.
Actually, I personally don't mind at all, except feeling a little sorry for those low-level students I find it hard to get through to. I have zero responsibility, zero pressure, and absolute freedom to teach what I want and how I want. It all probably makes for a breath of fresh air for many of the students in my school and a break from their usual monotonous routine, and the intellectual freedom it allows me is quite fulfilling. I do, however regularly get the feeling I am teaching the kids about Western culture and life rather than improving their English. While this might actually be valuable, I am fairly sure it is not what the Korean government intended when they embarked on hiring NETs from Native English speaking countries.
The policy regarding NETs the way it is, I really don't blame my school - and others like it - in how they deal with my classes and their lack of care when it comes to providing quality co-teachers. Good Korean English teachers with a high enough level of English to be useful in class with the NET are in short supply and I can imagine they are needed for their own lessons. Priority number one for schools is to help students pass their final exam at high school with flying colours, so they can make it to a reputable university. Despite some research showing that NETs can improve English ability in high level students, their efficacy the way things are is negligible and this is not surprising for the reasons I have already mentioned and the fact that exams are not really geared to speaking and genuine communication. If I was a principal in a school in Korea, I wouldn't put much of my time into the foreign teacher either.
I truly believe in the idea of importing foreign teachers to teach students about language and culture, this is genuine education, especially if it is done well. It is not learning culture or language from a book it is experiencing it, interacting with it, and understanding it first-hand. But the fact is that when it comes to getting students into a good university, the foreign teacher and true education is surplus to requirements.
* Originally "legal requirement", my mistake, sorry.