I good topic for a lesson would be an update on the filters available in Photoshop. Stretching the title definition a little I am thinking of:
1) The new Neural filters, e.g. real world examples using the depth blur. It looks an interesting filter.
2) Sky replacement, not really a filter but an update to using Photoshop’s sky replacement as opposed to making selections. Maybe this needs it’s own lesson not sure but combined these two would fill an hour.