Blonde phys-ed teacher

A blonde gets a job as a physical education teacher of 16 year-old's.
 
She notices a boy at the end of the soccerfield standing alone, while
all  the other kids are running around having fun kicking a ball.
 
She takes pity on him and decides to speak to him.
 
'You ok?' she says.
 
'Yes.' he says.
 
'You can go and play with the other kids you know' she says.
 
'It's best I stay here.' he says.
 
'Why's that sweetie?' says the blonde.
 
The boy looks at her incredulously and says,
 
    "Duhhh.....Because I'm the Goalie !" 

Thanks Norman