A hack or an hack?

This morning was grey and still but dry and mild. Dad and I went into the school whilst Other Dad took Dibby on a hack..or should it be "an hack"? Whatever the gramatically correct version of what Dibbs did, Dad and I schooled.

We worked on a long rein large for quite a while concentrating on going forward and straightness and then worked through walk, trot, some lateral work, transitions and canter. We practised Prelim 1 and also did some canter going large with a lighter seat. Again Dad was pleased with our progress and we came in for grooming, an apple and some minties. Dibby arrived back when I had been groomed and we were put out to graze together for the afternoon.