There's a child Opal card. However, a high school Opal card would be akin to the T-card, which high school students got around in 2007 (this was actually the failed predecessor/trial to Opal).
lel, yea I know how u feel..I get mirin when people just tap on and tap off while I am the fucking idiot who is trying to collect coins for the $1.90 bus ride