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.
The US also lags behind most developed economies in preschool enrollment among 3-year-olds. Growth in demand for child care services may come from countries such as China, India, and Mexico, which have ambitious goals to increase preschool enrollments.