My drawing lessons and painting lessons in Amsterdam city centre are private, although I agree to teach to couples or small groups.
What I like to offer is what I would have liked to receive during the limited painting instruction I once signed up for, and which to my mind did no deliver. Given that I have a house studio, this allows me to deal with 1 or 2 people at a time.
Most painting classes have you come to an atelier or studio and paint away. The price may be per lesson or per 'course' and you are told that you can get 10 three-hour lessons for 300 Euro. You do the math in your head and think "WOW, I'm paying only 10 Euro per hour to learn how to paint!"
That's the first mistake. In reality, you're paying 10 Euro per hour to paint somewhere and receive occasional (and perhaps very good) advice on how to do it. These are not 30 hours of learning, they are 30 hours of painting or practicing. It is not the same thing.
This distinction is crucial, when you start to realize just what a time consuming activity drawing and painting can be. I will say this as clearly and plainly as I can: It makes absolutely no sense to put in the practice hours while at the same time paying someone.
This is the first reason that my Amsterdam painting lessons and drawing classes are private. They separate learning time from practice time. No need to pay me while you're taking all the time in the world and doing things you already know how to do. Do that on your own (literally) free time. The time you pay for, next to an instructor, should be spent making the most out of what this person knows, asking all the questions, discussing the work, learning a new technique and how to apply it, etc.
The drawing and painting you actually do during these lessons is focused on the learning of one specific thing or technique. You try the technique out, see if it works and figure things out with the help of the experts. Then you practice it on your own time.
Compare this idea with that of learning how to play a musical instrument. You don't pay a teacher to come over and ring away at your guitar for 3 hours. You sit down, discuss and learn what needs to be learned and then during the days between lessons you do all the ringing away and the practicing.
The second reason why my Amsterdam painting lessons are private, is that of positive criticism.
Not everyone knows how to give it, and not everyone knows how to get it, but it is a crucial part of improving. It is well known that you must become your harshest critic and the great masters of art always were. If you let things go, and cut yourself slack, the results may not be as good as they would otherwise.
A few things tend to happen during a painting lesson with this regard. Other members of the class may be too encouraging to keep things nice, or perhaps each will have a totally different opinion about what to make our work improve. You may not be comfortable receiving criticism from them or from the teacher in that setting. Finally, you may begin to compare your work to that of others and draw unwarranted conclusions about your own talent and capabilities.
In a private setting, you can openly discuss the bits you find challenging and receive a stern criticism about your work from someone who is an expert and who's job it is to raise your artistic level, without the risk of feeling like you came short. You are there to learn.
Then there is the obvious stuff during painting lessons, such as the fact that the teacher's attention is solely dedicated to your work, you can choose your subject with more flexibility and even call the shots about when and how to take a break.
Contrary to the social and fun idea we have about painting lessons, an atelier with practicing artists is usually as quite as a mausoleum for most of the time. The painting 'lessons' with a real social value, such as the 'wine and pallet' types are great fun but you will not make great progress beyond what you already know.
Anyway, that's my take on the whole private lessons bit!