In the US the first stage of compulsory education is generally known as elementary education. It takes place in elementary schools which usually incorporate the first five grades and sometimes have a kindergarten. Elementary schools in the US are also known as grade schools or grammar schools. In some schools, teachers utilize a "looping system" where the same teacher teaches the same group of students for two years. For example, a third-grade class may have one teacher who would teach those students for an entire year, then that teacher would teach fourth-grade the next year, and thereby teach the same class again. The teacher would then revert back to the third grade the following year to start the process all over with a different group of students.
Over the past few decades, schools in the USA have been testing various arrangements which break from the one-teacher, one-class mould. Multi-age programmes, where children in different grades (e.g. Kindergarten through to second grade) share the same classroom and teachers, is one increasingly popular alternative to traditional elementary instruction. An alternative is that children might have a main class and go to another teacher's room for one subject, such as science, while the science teacher's main class will go to the other teacher's room for another subject, such as social studies. This could be called a two-teacher, two-class mould, or a rotation, similar to the concept of teams in junior high school. Another method is to have the children have one set of classroom teachers in the first half of the year, and a different set of classroom teachers in the second half of the year.