[latchkey]

The issue is that the teacher needs to actually change the pressure in the room in order to create enough airflow. The fan in the hall needs to create a greater pressure (push air into the room) and the fan in the window needs to remove the pressure. If the fan in the window is stronger than the fan in the hall, then there will be a negative pressure (suction) to pull air into the room.

The problem is that the room probably has leaks such that if the fan in the hall is creating pressure, then the air doesn't all escape through the window. It'll escape through the path of least resistance or maybe even just spin inside the room (hot air rises too). If there is two doors for the room, some of it may be escaping under the other door. In that case, then air is just circulating back into the hallway. People also forget to take into consideration the expansion of hot air, which I've seen quotes for being up to 6x the volume. This complicates the pressures in the room.

As mentioned elsewhere in the discussion, the kids probably wanted to feel cool via evaporation since neither of the fans was moving nearly enough air to cool the entire room enough.

I run a couple large crypto mining farms in a pretty hot country. The 'kids' generate the heat and we have to move large amounts of air through them in order to keep them relatively cool. I've had to learn a lot about airflow design and it sounds very similar to what your teacher was trying to achieve.