在校期间用英语可以说"during school"或"while in school"。

"During school" 是由"during"这个副词和"school"这个名词构成的短语，"during"在这里的意思是"在……期间"，"school"则指的是"学校"。例如：

I studied hard during school. (我在校期间很努力地学习。)
He played sports during school. (他在校期间参加了体育比赛。)

"While in school" 也是由一个副词"while"和一个介词短语"in school"组成的，"while"在这里的意思是"当……的时候"，"in school"则是"在学校"的意思。例如：

I learned a lot of new things while in school. (我在校期间学到了很多新东西。)
She made many friends while in school. (她在校期间交了很多朋友。)

希望这些例句能帮助你理解这两个短语的用法。