Preschool is your child's first experience with a learning environment, if the experience is poor it can and often will influence a child's attitude and behavior in and toward school for their entire school career.
Academics are great BUT they should be SECONDARY in a preschool -I say this from experience and I know that many parents have been coerced into thinking that their child will do poorly in regular school if they don't learn a lot and "get ahead" in preschool. This is a misrepresentation of the purpose of preschool. YES children do better in regular school if they have had a positive experience in a QUALITY preschool program. A quality preschool program stresses building up a child's self-value, self-confidence and develops a child's natural sense of curiosity about the world. IT DOES NOT stress academics, sitting for extended periods of time, raising hands, names on the board, shame tactics, a quiet environment, or perfect behavior. Sometimes a stern voice is needed to maintain order, but I don't think that it what you are sensing-I think you have found yourself faced with a preschool teacher that doesn't allow preschoolers to be preschoolers. Preschoolers are not Kindergardeners, first graders or college students!
According to DCFS standards preschoolers should NEVER be shamed, forced to sit for more that 10 minutes unless by their choice, and the environment should be play-based and inviting. In my professional opinion preschool teachers should be happy, confident, warm, and gentle and understand some basic preschool behaviors and attitudes, if this teacher doesn't then why would anyone send their child to her class?!
If you have any doubts and you can change the teacher do it NOW. Never apologize for your feelings or parental intuition. You are paying for this service and it is your right to expect your child to be in an environment that will best suit their needs. Remember once you get into public school it will be MUCH harder to make any changes (as I am learning already only a month into Kindergarten).
FYI I ran a preschool and have taught for over 10 years so I know it can feel awkward to request a change, but a good director will understand and oblige you. Just don't be confrontational simply tell the director in confidence that you are concerned that there may be a personality conflict between your son and the teacher and you prefer a switch. When she encourages you to try the class politely refuse and insist that your child be switched to a different class. Tell her that it makes you more comfortable and since you pay the tuition you'd like your request honored. (Bring your husband if you can and have him back you up). Apologize for any inconvenience but remain firm. BUT if the director is really good she will have a valid reason to back up her staff members-if she doesn't I would be leery of keeping your child enrolled. A weak director will make excuses for a staff members attitude but good director won't and will instead tell you why that teacher is employed and why she believes in her abilities. So, take that into consideration too-if you end up feeling comfortable with the director's reasoning you may want to concede, if you aren't satisfied DON'T BACK DOWN.
Preschool should be fun and hands on and exciting, if it isn't then it is definitely NOT a quality preschool program.