us school ages

In the USA, children start school when they are five or six years old. Depending on the state, schooling is compulsory until the age of 16 or 18. Children younger than five can go to a nursery school or preschool.
At the age of five or six, the children attend elementary school (also known as grade school or grammar school), which last six years. The fist year at elementary school is called kindergarten.

Did you know that 80% of a child’s brain is developed by the time they turn 3? Yet children from low-income families hear roughly 30 million fewer words by age 3 and can enter school more than 18 months behind their more affluent peers. In fact, millions of kids living in rural America don’t own a single book. That’s why early learning opportunities are so critical for children, regardless of their family’s income.
Our education experts work across rural America, providing early learning opportunities through Early Steps, Early Head Start and Head Start programs. Our school-age programs provide supplemental support to struggling readers during school, and in afterschool and summer settings. These programs are proven to accelerate achievement for at-risk children and have been replicated in more than 100 communities across the country.

References:

http://www.savethechildren.org/us/what-we-do/us-programs/us-education ^(https://bannerad-design.com/goto/http://www.savethechildren.org/us/what-we-do/us-programs/us-education)
http://www.goodschoolsguide.co.uk/international/uk/london/international-schools-considered-by-expats ^(https://bannerad-design.com/goto/http://www.goodschoolsguide.co.uk/international/uk/london/international-schools-considered-by-expats)