Hi Stranger_UK,
As a language teacher with more than 25 years in the career, I can tell you from personal experience some very important observations.
Both group classes and private classes have their own advantages and disadvantages, however I firmly believe that the advantages of private classes outweigh the disadvantages; they may even outweigh the advantages and disadvantages of group classes.
The only disadvantage of private classes (aside from price, which actually you should look at as an investment rather than an expense) is that during the class dicussions you have only two points of view, yours and the teacher's. This sometimes can limit debate which will help greatly in the learning process. However, having said that; a good teacher should be able to present various different opinions or facets of an issue which will compensate for this loss and generate a further exploration of the different sides of an issue.
The advantage is simple, you have the undivided attention of your teacher. Your teacher isn't occupied with resolving learning issues with other students. Let's imagine you're in a class with five other students; your teacher has exactly ten minutes to devote to each individual student under ideal circumstances. If a student has a serious problem our doubt that requires assistance you may end up getting much less attention during a given class. Also, you progress at your own speed unlike in group classes where you will either have to keep up to the most advanced student in the class or you will end up being held back in your development by the weakest student in the class. Neither of these situations is very good for your learning experience.
Depending on the school, group classes may or may not be less expensive. Schools usually charge high fees, which may be two or three times more than what they pay the teacher. These administration costs are rarely divided among the students, but rather used as a means for the school making a greater profit. Conversely, private teachers will charge a fixed price (usually what they're accustomed to being paid by a school where they've worked or just a little bit more than that figure). Private teachers may also give discounts of their fees for additional students as opposed to the fixed fees in schools regardless of class size.
In traditional schools you have to go to the teacher, and depending on the location of the school and your residence this can increase your costs and consume much of your time. Private teachers will often come to you; they may even offer classes given on Skype or other such network reducing your costs and consuming less of your time. Certainy teachers will factor into their fee the costs of transportation and the time they spend in transit, however this rarely increases the fee you pay to what you would have otherwise paid had you enrolled in a traditional school.
Regarding the fee a given teacher charges, a lower fee may not necessarily reflect a teacher with less experience or qualifications than a teacher who charges more. Sometimes it simply is a reflection of how competitive the profession may be in a given area. Teachers may be forced to undercut the prices charged by other competitors in order to maintain a decent student roster and work the maximum number of hours possible. Like the old saying goes, "You can't judge a book by it's cover."
What you need to do in either case, private classes or traditional school, is to find out as much information as you possibly can about your teacher's previous experience, educational background and if possible obtain references from other students who can give you their own insights into the level of teaching they received and their satisfaction with their own progress.
I hope that this information will help you make an informed choice as to which way you intend to map out your educational plans.
Cheers,
William James Woodward Brazil Animator, Expat-blog Team