A training height fence (I thought it was like advanced)

We had a jump lesson today.  Charlie had the prior two days off while I was at work in Seattle, so during warm up he was soft and forward, but still a bit stiff.  We warmed up, walked a bit, but the softness and forward disappeared in between, so we had to start with a bit of a grind in the canter.  If I took up the reins, he would make his steps very short, so then I'd have to bend him to the outside and he'd slow down to like slow motion.
That was the downside.
The upside was he jumped beautifully.  The problem with the jump night at home, when he was long and flat, was that I'm a moron who doesn't know how to measure, didn't think to check, and as John pointed out, could easily have texted him to ask.  I made ground poles 12' on each side of the fence but they should have been 9'.  12' is pretty much a recipe for making Charlie jump long and flat.  Live and learn - thank god I've got Charlie who gave it his best even with a nincompoop for an owner.
So we started with a little vertical, and then John whopped it up what looked like a foot.  This had two properly spaced ground poles, and we jumped it on a circle from both directions.  The circle was just a bit tight (20 meters, though, but it felt tighter) and Charlie actually did pretty great landing on the left lead.  Our second time through (to the left), he wasn't as good, but he was pretty quick to change in the front and it usually took just a few tries for the hind.  But by the end of the lesson, he was struggling to change, so I think that's good information; it is not just a mental thing but also a strength thing.
Then John added in an airy vertical over some flowers, which he said was a hole up.  I think that one was about 3'.
Then he added in a little lattice wall with a vertical on top, which looked freaking gigantic (I was sure it was armpit height; i.e. 4'2") which Charlie jumped like a dreamboat.  Afterwards, I checked, and it was only 3'3".  So my eye has some adjusting to do, but Charlie got right back to it.
I thought Charlie did great on the flying changes; it rarely took more than a couple laps for the full change, but John said that when he changes in the front, I don't need to bend him to the outside to get him to change to the back; that will just encourage him to change back to the right in the front.  Instead, I just need to pull my outside leg back (the right leg) and do a half halt with the outside (right) hand.  Once I quit making too big a deal out of it, he popped in like a dream.  I think he's catching on, and I hope that his back to work was more proper working so his back muscles are building up.
John said this week to practice on the left lead; do a jump and go to the left over and over and make him change if he doesn't land properly.  Next week is dressage, and then in February we'll go back to two lessons a week.
It was super fun jumping, but using my legs to line up the circle with the fence was hard to keep consistent.  Every once in a while I would hit it dead on and feel it coming, but most of the time I was still wiggling right up to the end.
Charlie is such a good boy.  He's a total trooper.