Most of these upcoming exercises will be easy for a young, green horse.
They are designed to be worked in order. Each task should be completed, and ridden until the horse is 100% reliable with the particular setup, before moving on.
The first step to get your horse comfortable with Jumping Gymnastics is trotting poles. Depending on your individual horse, the measurement between poles will be 3-5'. For example, my 14.1hh pony can comfortably ride any distance. But when I first started working her, she couldn't do anything but about 3.75'. The easiest way to determine what is comfortable for the horse is to lunge them over poles. This ensures that when the horse takes a funny step trying to accommodate the new exercise, a rider's balance won't negatively impact their stride and impulsion.
Of course this means your horse will need to be reliable on the lunge line.
So, lunge your horse over poles, starting at 4'. If he takes 2 steps between sometimes, scoot them a few inches closer. If he skips a pole sometimes (taking two poles in one step), they need to be spread apart a bit more. If he attempts to canter, move the poles closer. Keep working on adjusting these poles over a few different sessions to find his most comfortable stride. Later you can adjust the poles to achieve different training results. Ill talk on that later.
Once you find your horse's most comfortable trot step, you can start adding in variety. I like to use the mantra "Do it until its boring". You are training your horse by using these tools. If you rush through, or skip sections, or don't thoroughly cover one piece, you may end up having to fix things later, or you may end up with a horse who is only comfortable and coordinated in certain circumstances.
Remember to reward your horse. Each horse is an individual. You must learn to adapt to what your horse enjoys most as a reward. For most horses, simply coming down to a walk on a loose rein is a good reward in the early stages of training. Some horses pay enjoy a trot on a loose rein, and others may want to stand completely still to absorb the lesson. Bonus, if you haven't heard of clicker training yet, a clicker can be a great quick reward to let the horse know he has completed the exercise successfully.
The next step is Canter poles.
Make sure that your horse is confident and willing over trot poles before trying multiple canter rails in a row. If you need extra time on trot poles, but you are going stir crazy, try cantering just one single pole instead.
Canter poles in general should be placed 9-11 feet apart. Depending on your horse and his ability and coordination. What you do NOT want is to have them at a full canter stride (12') as very easily this can turn into the horse getting strung out and reaching too far.
Rinse and repeat until these exercises come naturally to the horse. The time this can take will vary greatly, depending on the horse and rider. Its best to set "check in" points, rather than an end date for each exercise. When you are ready to move the horse to the next level, he should be happy trotting a straight line through the poles, cantering over trot poles, in different areas of your riding arena. Move the poles to create variety and increase the horse's confidence. The secret is to keep 1 piece the same, and change others. For example, use the same trot poles, but move them to a different spot where there are different shadows. At this stage of his training, it would be unfair to expect the horse to accept all factors being changed every time. You have to learn how to listen to your horse and what he is telling you.
horse balks at the poles - If your horse stops forward motion, he may need a refresher of the basics. He needs to respond to leg, voice and weight cues, at least on a rudimentary level, to accomplish these tasks. If they are not solid, go back to the lunge line, and associate a word or noise with "go faster". This can be accomplished by saying the word (or clucking) at the same time as swinging the lunge whip towards him. Then under saddle, use that same word or phrase at the same time as a light tap of the riding crop behind your leg. If your horse doesn't respond, go back to basics.
horse leaps over the poles - If your horse takes a superman leap over the poles, try to simplify the exercise until he learns how to "see" the poles. Remember they do not have the same depth perception as humans. For example, you could go down to 1 trot pole until she learns what it feels like to trot over the poles.
horse veers/weaves/drunk drives over poles - If your horse trots/canters as though hes had too much to drink, its very similar to the last problem, he is not responsive to leg/rein cues and probably should go back to basics. Talk to your trainer about lateral cues and how to get the horse more responsive.
1. Before starting, horse must know how to ride straight and forward, and lunge.
2. Lunge over poles if he has not been exposed to them before or has confidence issues.
3. Work the trot poles before moving to canter poles
4. Horse should be confident, reliable, and predictable before changing the exercise.
This is the foundation for all jump training. You are laying the foundation for a life skill for the horse. Do not rush through this. Just like building a house, the foundation is extremely important.