Novice geometry & my concentration

I decided to start working my way through the new dressage tests on days when we're not working on something else, so I started this week with the new Novice A.  It had a two loop serpentine from A to C and I wasn't sure what was intended by a "two loop serpentine".  Not surprisingly, I was overthinking it.  John said a dressage arena is 40 meters long, so it is 2 1/2 20 meter circles.  In other words, it is a counterclockwise circle starting at A with a change of direction at X and ending at C.  John said that the gotcha will be heading to C, not making the round circle, but riding straight into the corner.
From there, we went to work.  Duke felt light in the warm up, and yesterday, although our transitions have felt a little rough.  And miracle of miracles, John had us work on transitions.  He said that Duke can do it, and I shouldn't just accept the rough transition, but ease him into it - get the bend and then keep the bend all the way into the transition.  We did trot up to canter and then canter back down to trot, and, like riding each step of the circle, it just required me paying attention to each step.
Interestingly, Andrea and Allison were wrapping up, and were being hilarious, and John noticed that when I was paying attention to them (and talking back), Duke got more round and on the bit than when I was actively trying to make him round and on the bit.  Very interesting.
In addition to transitions, we continued to work on the shape of the circles.  John would have me make a 15 meter circle, and then he said to hold it on the 20 - there's something about making the circle smaller that makes me concentrate, but he said it's riding the same out on the regular 20 meter circle.
We ended because Duke was calm and was trying.  John said for now, we want him to be less anxious, and so his reward is to stop when he tries and gives, and that it's not a big deal.  He said when we go on to lateral work, the lessons will be longer because Duke will start to react, but the big lesson for him right now - which is obvious in how much more relaxed and balanced he is about the work - is that it is ok to do what I ask and not fight about it.
I also felt like he was just really balanced today - it is harder to sit up in the canter - John was right a few months ago, it really does kind of lurch me forwards - but I can do it so long as I concentrate.  But his trot, I felt like both my legs just wrapped down and around him and I was glued to the saddle.  I'm not sure if it was him or me or both of us, and maybe related to the extra time in the gym, but it felt like we were really connected.