Sunflower seeds

Somehow, I just asked myself why Mr. Sir eats sunflower seeds.
I believe that it represents the attidude of the guards of "Camp Green Lake" towards the boys. The boys are not really bad and do not have a bad character. For example, Zero who is said to be completely stupid. Yet, he is actually good in math. The boys talents could be seen as small hopes which still have to grow, just like the seeds Mr. Sir eats. Therefore, you could say that by letting the boys dig every day instead of teaching them stuff the could use in the real world, the guards destroy the small seeds of hope and opportunity the boys have.