下课后的那十分钟多愉快下课前的那三分钟最难耐
[xià kè hòu de nèi shí fēn zhōng duō yú kuài xià kè qián de nèi sān fēn zhōng zuì nán nài]
This describes the mood swings during school time - the impatience before the class ends and relief after it ends. Reflects students' shared experiences about classes.