Answer:

The hottest part of the classroom is likely to be near the ceiling. This is because hot air rises and cool air sinks. When the air conditioning unit is located in the center of the room, the cool air will be circulated from the center and will move downward. As this cool air moves downward, it will meet the warmer air rising from the floor, and the two air masses will mix. As a result, the overall temperature near the floor and center of the room will be somewhat cool and even throughout.

However, the hot air from inside the room, such as from student's bodies, light fixtures, or equipment, will rise toward the ceiling and accumulate there. This accumulation will form a warm air mass near the ceiling that may not mix as well with the cooler air masses near the floor and center of the room. As a result, the hottest part of the classroom is likely to be near the ceiling, where the warm air is located.