With schooling Harry I've been using some of the exercises from the 101 Schooling Exercises book (with an imaginary arena). After his usual warm up of walking and trotting on a long rein until he felt a bit looser, we started with Ex. 17, establishing working trot on a circle, then lengthening his trot out slightly across the diagonal, collecting him up again and coming to a halt. Lengthening then coming to a halt was good for him, pulling up and getting his back egs back underneath him beofore he go too strung out or hyper in the bigger trot. After doing this a couple of times each way I added a rein back after the halt.

We went onto Ex. 19, lengthening and collecting trot on a circle, which I think he did a lot better after doing the last exercise, he thought after lengthening that he was going to halt, so he was more ready to sit down and bring himself back, if he was a bit slow with it I just halted him again to remind him.

We finished by doing this same exercise in canter (Ex. 20), just pushing him out gradually for a few strides and then bringing him back before he got too excited about going fast, and building up the amount of strides we did.

Used the same exercises for Giant, but with him the emphasis was on the go rather than the stop parts. So with him in Ex. 17 I made the trot on the circle quite slow and started to build his trot up before the diagonal, then pushed him out as much as he could go on the straight line without falling on the forehand or trying to canter, then halted, sometimes also asked for a rein back, somtimes not, just to keep him thinking and listening. And again, the go after the halt is important for him, getting him to spring back into trot.

Ex.19, trans within trot on a circle, I do quite a bit with him anyway, but is still a very good exercise for him. And with him you can make a much bigger difference in his trot than with harry, brining him right back to a walk speed (but in trot), then focusing on getting him sharper off the leg so he would go forwards better and not disturb his balance.

Ex.20 in canter I modified a little, pushing his canter forwards on a bigger circle, then making the circle smaller as i slowed him down again so that he wanted to bring himself back, and the smaller circle means he has to bring the inside hind under himself more as he collects.