Hi Wep, I like the colors and the idea of gaps in the briefcases. Maybe briefcases aren't the right object to use as we don't want to be associated with executive jobs but more like casual jobs. It will be good to explore objects such as clock, half a man (student). It can be very teasing or playful as we want it to be memorable and catchy to students. Characters, mascots or caricatures can have a good appeal to students too. So, if they can be somehow integrated in the logo in a very original and unique way, it will be great. The font is good as it is easy to read, but maybe some more student like font can be used. Also, you can always explore the idea of having the letter A in the middle in a different color or even an object with the letter A. We are happy seeing some very strange ideas as well as long as the logo is very unique and catchy to students.
I like #3 the most so far. How about adding some clock hands in the circle in the middle, giving the idea of a clock. Not sure if it will be clear, but it's worth trying as it will give an extra idea of time. The character on top is very good. Nice work.