Have Fun, Trainees!

Josh exited the Alter Tower, having lost all notion of time. Luckily he had a trusty clock: So it had been two days already. Not too bad. Instantly people noticed his arrival. 

"Teacher is back! You all, he's back!" 

"Hey, am I going crazy, or was that light purple?!" 

"Please, everyone knows Tower light is red." 

"What do you think happened in there for two days? So mysterious!" 

"Who knows…" 

The 300 of them were slowly gathering, with many exiting the newly constructed buildings. Josh trusted that Bob would do a great job. He took a breath and hollered at them. 

"Alright, everyone. I have great news: the Alter Tower is finally operational for training! We'll do it like this: a third of you guys will stay behind to watch over the camp. As for the others, have fun inside!" 

"What are we supposed to do in the Tower?" One raised his hand, perplexed.