So yes, any one taking a trial lesson will wear a parachute if at all possible and will receive brief instruction in it's use.
In a glider, perhaps.
There isn't much to say as they are circular reserve-style chutes designed and packed to open very quickly, and they can't be steered like a square one can.
Ram-air canopies open very quickly, too, which is irrelevant. Round canopies can be steered, and this should be part of the instruction, as should how to address certain malfunctions, how to land, how to collapse one's parachute on the ground (especially for those that can't be cut away), etc. Line twists are common in ram air and round canopies. Pendulous motion (swinging) in round canopies is common.
That policy has saved at least one life - both occupants of the K21 that was hit by lightning near Dunstable survived with relatively minor injuries.
If you're referring to a Schleicher ASK-21, the obvious question would be why the aircraft was being operated near thunderstorms in the first place. Convective activity and lift, yes. Thunderstorms, no. Bad idea. Welcome to the Darwin Club.