Open up outside area in the Hangar
To open up an area that goes outside the main part of the hangar simply grind across on of the Helicopters blades
Open Up The Gym In School Level
To open up the gym a secret area that has a pool with diving boards and a basketball court with ramps you need to grind the Opensezmee Rail before the bell stops ringing at about 145 or so Grind the rail as the bell starts ringing though and not before it begins The gym entrance is underneath the overhang looking straight ahead from the start