Difference Between Convergent and Divergent Evolution. When considering living organisms, evolution can be defined as the development of differentiated organisms from less differentiated pre-existing organisms over the course of time. There are many sources, which provide evidence to the theory of evolution.
You're apparently differentiating between daycare and preschool, right? Private preschools (about $500 per month for three days per week, 9:00a to 1:00p) typically have a minimum age of 30 months (2.5 years) and potty-trained.
In Iowa, children enrolled in preschool programs (4 years old on or before September 15) are considered to be of compulsory attendance age. Each city and parish school board may provide for a child younger than 5 to enter kindergarten if that child has been identified as gifted by the state guidelines.