FInal Idea

The children standing up, we cannot see their faces. They seem to be standing in a military fashion, no movement and measured to perfection away from each other.
The Teachers hand is seen mechanically writing on the black board.
The children are shown to be robots with light bulbs on their heads.
One robot looks out of the window and sees a butterfly. He then imagines the butterfly flying into space and transform into a spaceship.
The robot starts to malfunction explodes into a smog of colour, which reveals the robot as a child.