Middle school:

Middle school; Middle school (children aged 9 to 13 in Britain); American middle schools for children aged 1 1 to 14; Junior high school;

Plural number: I met David in the second day of junior high school.

On my second day in middle school, I met David.

When I graduated from middle school.

When I graduated from middle school.

This idea comes from four students in Tianjin Zhongbei Middle School.

The idea came from four students in Tianjin Zhongbei Middle School.

Most of my reading in primary school, junior high school and senior high school is factual reading.

Most of my reading in primary school, junior high school and senior high school is factual reading.