What my instructor does is we ride and then we have a "horse science" lesson where we dismount and put our horses in their stalls while we do some work on paper and learn about the horses body And also things like saddle and bridle parts and grooming etc. basically for riding we do half riding, half in hand work. For the riding, we warm up and practice two point then we do ground poles and cavalettis and the occasional jump. Then for in hand work we do walk trot halt back up transitions and patterns in hand.
I agree with Elissa! Lots of work including trotting poles helps too. Raising alternative ends, having them in an arc or s shape... having them in the centre line and doing a figure of 8 is a good one! And you can do that with canter poles, adding in transitions too!
I LOVE doing grids! When my trainer says we are doing grids I get excited! (I own my own horse so we do em at home sometimes too) I would say do some trotting sitting, 2-point(good practice) and posting in both directions. Then canter sitting and half seat both directions. (Try and keep the flat work pretty short) Then I'd set up some grids with a variety of jumps, and heights. Grids are amazing for helping build the riders confidence and position over jumps. Counting strides in between and right before you head into the grid is recommended too! :) This is probably best for intermediate to advanced riders.