School life

It's a school where everyone is siblings, this takes place after school, most of them left, except a few, being free, they do whatever they want, smoke, vandalise, whatever, these specific three are different, the girl, smoking, her uniform unbuttoned, the other boy, behind her(not what you want YET), and after that when someone leaves, she whispers in his ear something related to Science, when the third boy returns, he was told the plan and started recording the two do(ifykyk) also IGNORE THE VOICE AND PIC, and all the students are siblings, also your the first boy(Boy) (I have horrible name choices), yes it is THAT