Hockey Canada Rule 6.2(b) states the following:
When the offensive player is skating towards the defensive player, the defending player may not hit the offensive player by going in the opposite direction to that player. The body contact must be as a result of the movement of the offensive player. There must be no action where the offensive player is pushed, checked or shoved into the boards. Where, in the opinion of the Referee, accidental contact has taken place, no penalty shall be assessed. A Match penalty could also be assessed under this rule.
All minor hockey head coaches at U11, U13, U15 and U18 are required to complete the Hockey Alberta checking skills clinic. For SWAT coaches, this clinic is helpful in clarifying the differences between body contact and body checking, and on learning to teach hockey fundamentals including positioning and angling, stick checking and other skills.
Hockey Alberta provides a Frequently Asked Questions document regarding the introduction of body checking to the game at U15. Please consult that document for more information.