Fundamental Forces of Flight
Below you'll find diagrams of a glider and its various parts. Terms like aileron, elevator, and spoilers will be used very frequently in your training so familiarize yourself with them.
Axes of Flight
Making turns in a glider can be a bit of a challenge. It is important to use both the ailerons and rudder in a fashion that results in a coordinated turn, one in which the yaw string is straight up and down in your windshield.
If you turn using the ailerons (stick) only, you will encounter a phenomenon called "adverse yaw". This describes the tendency of the glider to yaw toward the raised wing in a turn, due to the increased drag on that wing, as a byproduct of its increased lift.
For example, as you turn left, the left aileron goes up, and the right one goes down. Because the right wing now produces more lift, it also produces more drag, resulting in the glider yawing toward the right wing as shown in the slipping turn below.
Of course, you can also use too much rudder, resulting in a skidding turn as shown here.
Here is what the yaw string in the windshield looks like in those rare moments when we are able to turn in a perfectly coordinated way. You may not see this often (at least not from me), but it's glorious when you do, and it's your goal during every turn!