Can III Grade students plot a teacher's assault?

I read this news report in today's Dallas Morning News about a mixed group of class III students plotting and almost executing a murderous attack on one of the class teachers. Apparently the group had planned the assault well and brought necessary tools such as a broken knife, steel handcuffs, duct tape, etc. Luckily for the teacher one of the students who was not involved in the group revealed the plot and the school called in the police.

What is more shocking is the plan itself than the seriousness of the plot. How could third graders make such a serious criminal plot? Are children here so smart, cunning and downright ruthless? All that I remember of my third grade years is being forced to do math and read by teachers and parents. Apart from that it was play, games and fun time with my friends in class. But today's third graders seem to be very vindictive and ruthlessly cruel.

Agreed that the world has changed over the past couple of decades. The education system is far more advanced than it was when I was in grade III, but is this what is being taught to students? Where is the innocence of childhood? Childhood for me means long days of playing; eating ice creams and chocolates without worrying about putting on weight or contracting diabetes; visiting grand parents during holidays; play innocent pranks in class such as flying paper planes. But this kind of plotting to hurt the teacher is shocking. What are the schools teaching?