Grade advancement (ex: moving from preschool to pre-k) is based on age, not where they are in development. So there will be kids in my class ready to learn the calendar, how to use the alphabet to make words, add, and understand, while there will be some who can hardly speak, so instead of advancing those that can, I have to tailor my lessons to fit the children who were never ready for my class to begin with.
Also, the ratio of student to children is too high. Try looking after 12+ three year olds, keeping them from killing eachother, making a lesson plan, getting them all to sit down and participate at the same time, scolding, and diaper changing(which they should not be in diapers anymore) all by yourself is practically impossible. The kids get moved around too often. There are so many kids that they can't focus and play time is practically all day. It's unsanitary, to boot. All those kids? It's impossible to keep up with who puts what in their mouth then give it to another kid.
THE WORST PART. We are a no time out place. We believe in toy redirection. If a kid has a falling out with another and they start beating on one another, we can't punish, or put them in time out. We try to distract them. Tell me something. If a kid never gets reprimanded for wrong actions, how are they going to learn the difference between right and wrong? They won't. They'll learn they get a new toy if they pull someone's hair out for not sharing.