I think that's what a masterclass is. If I see a flyer saying some X professional musician is giving a masterclass I'm assuming it's going to be 2 or 3 hours of

I think that's what a masterclass is. If I see a flyer saying some X professional musician is giving a masterclass I'm assuming it's going to be 2 or 3 hours of just ideas, tips, methods and his general vision about music.