Subject + 开学 + 了
开学 (kāixué) means 'school starts' or 'the beginning of a semester.' It combines 开 (to open, to start) with 学 (study, school). It is the opposite of 放学 (school ends) and typically refers to the start of a new term.
下周就要开学了,我还没买好课本呢。
Xià zhōu jiù yào kāixué le, wǒ hái méi mǎi hǎo kèběn ne.
School starts next week, and I haven't bought my textbooks yet.
每次开学的时候,校门口都特别热闹。
Měi cì kāixué de shíhou, xiào ménkǒu dōu tèbié rènao.
Every time school starts, it's especially lively at the school gate.
孩子们盼着开学,因为可以见到同学了。
Háizimen pànzhe kāixué, yīnwèi kěyǐ jiàn dào tóngxué le.
The children are looking forward to school starting because they can see their classmates again.