The trial lesson consists of:
Groundschool
airfield safety briefing – how and where gliders take off and land, what to watch out for;
glider briefing – how it flies, function of controls and instruments;
parachute briefing – when, how and why to use it;
In the air
flight – depending on what you want from the lesson this may include you starting to control the glider in flight, or may be limited to a demonstration.
The whole experience lasts at least half an hour. Time in the air will vary between 5 and 15 minutes, limited by the conditions on the day.