Its a serious prob.plz help!

Umm....see its a schul matter.it was biology class & i was a bit distracted our teacher had given us hw & i forgot 2 do it.i dint understand at 1st but suddenly i saw a gal coming 2wards me,she checked my copy & complained 2 our teacher that i hav'nt done my hw.our teacher got furious bcuz i was supposed 2 go out of d class before d gal came for checking but i dint as i said i was distracted.i tried 2 defend myself but things grew worse & now my teacher has asked my parents 2 cum & meet her.guys plz help.tell me hw 2 get out of this hell.hw 2 convince my teacher that my intention was not 2 argue wit her.she's vry strict & the worst part is that there is a high chance that she wil fail me in bio cuz she's vry partial 2.i hav really created a bad impression!