1. The mother prays and cries for his son to return or surivive from war, while the child plays with the plane simulating the war. Both the kid and the woman have different perspectives from the reality. The mother sees the events like something terrible and dramatic, while the boy sees them as an entertainment.
2. We can infer that the boy's dad died in war, so he grew up alone. He sees himself reflected in the mirror dressed with his dad's uniform, representing what war left on him. Just a uniform, a piece of cloth, no paternal figure.
3. Those trains may be taking pigs or cows, headed to the slaughterhouse. Those masks are the same that the students use, making a comparison. The kids are risen as pigs so then they can be taken to the slaughterhouse. It doesn't matter who they are. They all grow up with a conservationist education. They are all just the same for the fate that awaits them.
4. I see that scene like an idea of hope that the kid has. He imagines himself joining a huge mass of students releasing the wrath that they have within them, fighting against the educational system imposed to them.
5. It portrays a strict, demanding and conservationist education, with lack of freedom to think in another way. Somekind of dictatorship.
6. War is also portrayed, with a lot of blood and caricatures of the great powers and empires struggling between them, and all the hammers marching like soldiers to their death. Loneliness is also portaied, shown and represented by the boy, who grown up alone and now is drowning in the consequiences of war.
7. I believe that the message that the song is trying to send is not the one being interpreted by some sectors of the students. "We don't need no education" is being used literally. It should inspire the students tu improve their education system, not to stop studying. However, the use that the "colored" students gave to the song, is totally acceptable and loyal, showing us that "Another brick in the wall" has more than one meaining. It can have a meaning per person.