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.
Report Abuse. Preschools are fairly unregulated private programs, so children can start anywhere from age 2 to 4 depending on the particular preschool. It may just be a 2 year old, 3 year old, or 4 year old preschool, or they could have classes for two or all three of those ages.