Differences between British and American English: school
In both the UK and the US, school usually means a place where children are taught from the age of four or five until they are 18. American speakers also use school to refer to a university. In the UK, you say that children are at school during the day: The kids are at school until 3.00. In the US, you usually say they are in school, but American speakers also use in school when they mean studying at a school or university rather than having a job: She’s still in school, but she’s graduating in the spring.