4c8765c2__School_Football___For_Dummies_High_School_Rules_to_NFL_Rules_High_School_Rule
[NFL Rule] A player must catch the ball with both feet down inside the sideline to be considered inbounds. [High School Rule] 
A player is considered inbounds on a pass reception if he catches the ball with one foot down inside the sideline.
The Rules of High School Football - For Dummies