Usually that software isn't real-time. You tend to log in to some web app, pick some stocks, and at the end of the day your returns get updated.

The students with the highest return on investment usually win something, in my case it was my teacher smiling his ass off and congratulating me. In the above comment, they won a freaking trip to NYC haha.

Anyway what he's describing is that usually these aren't the best written software packages. After all, it's to emulate a stock exchange for 14 year olds so they can do a project with fake stock-picking for 4 weeks. Quite often the web app trails the actual data, so people just go to the stock exchange website, see where the price is headed, then buy/sell accordingly on the fake exchange. 5 minutes later the fake exchange updates the numbers by pulling from the real exchange. It's as if you're betting on a baseball game that ended in the real world 5 minutes ago, as to who will win.

Tl;dr, kids cheated on educational stock-picking programs because kids can query the results of stocks before their software does.