Circle
One of the most common figure in dressage that can help you with these transitions is circle. Circle puts horse into a situation where he has to slow down and organize himself to stay balanced, this creates a natural collecting effect. The smaller the circle the more horse has to work: jump under himself, slow down, sit more on his haunches, etc.Here are several ideas on using circle for canter-walk transitions:

• Canter toward a corner and start 10 or 15 meter circle. Upon finishing your circle and approaching the wall prepare and ask your horse for transition to walk. If you just started working on your transitions make circle closer to 15 m. When your horse's canter improves gradually diminish circle size.
• Rollback on a short side. Canter into a second corner of the short side of the arena and ride a rollback of 10 to 15 m in diameter. Upon returning to the short side right before the corner prepare and ask for walk. This exercise utilizes the short size and its corners to give the horse visual help. He will be much more willing to come back to walk when he sees a wall right in front of him.
• Spiral in. Start with 20 m circle and spiral in to 10 m. The smaller the circle the more your horse has to work. He may start to show signs of struggle. As soon as you feel that ask him to walk and continue spiraling to 6 m circle. You can then spiral out and pick up canter around 10 m circle, continue to spiral out until you are back to 20 m circle where you can ask for lengthening of canter to refresh your horse.
• Use your imagination to use arena and its four walls to your advantage. For example, instead of cantering large and riding circle in a corner, canter on the quarterline or center line and ride circle at the end of it.

Square
Riders usually think of a square exercise in canter as an advanced one used for teaching a horse canter pirouettes. This is a mistake, a rider is missing out on introducing a horse to the very helpful exercise. Do not think you must ride it as a perfect square with the corners. Introduce your horse to it as an idea of turning a big circle into a square by making corners as portions of smaller circles and introducing a straight piece in between the corners. This idea will encourage the rider to keep a horse more between the aids, be more focused and sharp and plan ahead because things happen very quickly in canter. With practice your horse starts to anticipate the corner and gather himself more which is exactly what you want to achieve.

• Ride a 20 m square at the end of the arena, this way walls will help you with two turns. Be brave and ride your horse straight toward the wall allowing him to turn when it is about 5-7 m left, inside leg must work a lot to keep him from falling on inside shoulder. Use half-halts to prepare for the turn, however, be careful. You do not want to pull your horse into slowing down. After a few squares when you start getting the anticipation of the turn and your horse starts to collect himself ask him to walk. Decrease the size of your square when your horse starts to show proficiency.
• If your horse can execute 15 or even 10 m circles in canter ride a square spiral from 20 m to 15m/10m. Make transition to walk on the smallest square.

Counter-Canter
Counter-canter has straightening and collecting effect on a horse. It can be very useful for transitions to walk. Counter-canter can help you introduce your horse to a transition on a straight line. If you haven't done transitions to counter-canter from walk this is a good time to start.

• Walking large shorten his walk through the corner before a long side, ask for slight counter flexion and finish your corner almost in counter-shoulder-fore position. Pick up counter-canter. Ride straight and when you approach the next corner prepare him for transition to walk. Do not let him start turning, ask him for a walk 6-10 m before corner and walk right into it.
• You can create counter-canter by doing a rollback at the end of a long side. Just make your rollback small enough to have room for at least a few straight strides before you ask for a walk transition upon approaching the corner.

When your horse starts to perform canter-walk transitions consistently challenge him with the following exercises:

• 3-loop serpentine with simple changes of lead
• Short diagonals with simple change of lead either at the end or in the middle of the diagonal. Ride 2 diagonals in sequence: from M to E from E to F
• Transitions to and from canter on the centerline
• Figure 8 on the short side with simple change of lead on the centerline.
• Sequence of transitions either on a circle, or going large. You can change the lead every time or pick up the same canter again. Mix and match, use your imagination. The closer transitions to one another the more difficult the exercise is.

Reminder: do not drill, refresh your horse with canter lengthenings on regular basis, and/or let him stretch while cantering on a big circle, use as minimum aids as possible, work toward invisible aids, keep your horse straight - use shoulder-fore position before transitions, reward your horse with a walk break on a long rein after an especially well performed exercise. ALWAYS be fair to your horse while working on difficult movements. They will appreciate that and work for you harder and learn faster.

Happy riding...