My high school had its own radio station, we did live play by play coverage of football and basketball. It shouldn't be hard to find kids who want to do sportscasting, but it is a challenge to make them sound great. We didn't just have play-by-play and color, we had a whole crew of 10-20 students! We also did halftime and postgame highlights (2 or 3 students, 1 to write the highlights, others to record them), news (we had 3 people for news because we also did 1 minute news-flashes between each quarter), home and away stats (2 people, makes the play by play and color announcers sound like they know all the details), and if we had enough people, home and away sideline reporters (2 people, 1 home, 1 away, listen in on what the coach says to the players, and possibly interview the coach after the game). Before we got an audio line installed between the gym and the studio, there was someone who ran between the gym and the studio to get tapes, so the broadcast could be almost-live. Its those extras that make the broadcast sound great. And you need someone to operate the equipment and cue the announcers at the game, and someone to operate the board at the studio, and someone to take charge of the whole broadcast. We have done a broadcast with only 5 people, and it sounds like crap compared to a broadcast with 20 people.
The best thing is to form a club at the school, and let anyone who's interested in doing sportscasting join. Train the students on each position. Hold an audition for play-by-play and color for people who initially feel confident to take those positions, and initially, take the best for those positions. Let everyone else work the other positions, and observe their progress. Rotate the students between each position so they get experience. When trying to get students who are interested, mention that they don't even have to know anything about sports to be on the broadcast team. As the students get more experience, the broadcast as a whole will sound better and better.