It builds up nicely.
This is a fairly good composition for beginners. I think the low rating here is probably largely to the somewhat mediocre sound quality. I especially liked the last few minutes where the structure becomes quite complex. One basic problem I foresee is that students are going to be confused by the 3-on-4 rhythms that you have here. I've been in a beginner band before, and I remember well what it ends up sounding like when somebody tries to do something smart with rhythms...
P.S. I'm guessing you use Finale or Sibelius to write these submissions? You can increase the volume of your files with a free program called "audacity" (it can do a lot of other things, but increasing the volume is fairly simple).