I need to know the name of this movie?

it starts off on a stormy night...its lightning, and a little boy is in his room and he looks out his window and sees flashing behind a hill..it wasnt a lightning storm after all so he tells his dad about it...his dad goes and checks it out and comes back all different...and the son notices that he was different the next day at brekfast....he relized that the teachers at his school are different aswell....and at the very end these big round aliens are chasing him, and he ends up in the spaceship..that is all i could remeber, please help me