Ball In and Out of Play ( Law IX):
" The
ball is out of play when it has WHOLLY crossed the touch line
whether on the ground or in the air". This means the
WHOLE ball has to be TOTALLY over the touch line. A ball
that touches the line or is on top of the line is NOT out of
play. 
Method of Scoring ( Law X):
"A goal is scored when the
WHOLE of the ball passes over the goal line". It's not a goal
unless the WHOLE ball has passed
over the goal line.
PLEASE:
Remember, coaches and referees are usually parents just like you, or players
just like your kids. They give their time to help make your child's youth
soccer experience a positive one. They need your support too. Always
remember to stay and keep your guests at least 3-feet from the sidelines of the
game and no spectators are allowed around any goal areas or the ends of the
field of play.