A new study finds the youngest students in a kindergarten class are far more likely to be held back than their older peers.

(CNN) — A backpack, lunch box, crayons and at least 10 hours of sleep each night are all things children need to get off to a good start in kindergarten, according to a new study. Researchers ...

The youngest kindergartners in any class are about five times more likely to be retained than their older peers, a new study states.

The paper takes a new look at data from Project STAR, a well-known study on small class size involving 11,000 Tennessee children who entered kindergarten in 1985, and follows up on those children.

The study has led to the creation of advocacy groups such as Ready 4 K and the Minnesota Early Learning Foundation which work to lower the number of kindergarten students in class.

The original study foresees a larger-than-average kindergarten class for the 2020-21 school year, too, with 181 students projected. This is because of a spike in births in 2015.