selected randomly to participate on a event

im not gonna say what event it is cuz they told us to keep it confidential but anyways, its not that cool or exciting cuz i got randomly selected to answer stuff to test on our knowledge. i would join but the dates that they scheduled are hassle for me. i have classes during that time and i think im just lazy and also scared. i have been debating on this the entire day and i dont wanna go even though this is a rare occurence that i was picked out by the school. there are like 40 of us anyways, and some of them didn't show up to the orientation a while ago, i wish i did lol. i already signed up but now, i want to back out. should i really do it? i have no motivation to do it, plus i have an exam clashing with that event. lol, i hope no one from my school sees this. the event test starts tomorrow and i want to make a decision tonight so i can tell my mom about it and she'll tell the school that i wont be joining lol.