One last category of modality is that of ability/potentiality, which may be expressed either subjective explicit (she can/can’t...) or objective explicit (she is/isn’t able to…). As H & M (p. 621) put it, ability “is on the fringe of the modality system” yet I think the implications of this for EFL learning are not highlighted often enough. Ability is mostly introduced with the ‘I can play tennis’-type lessons, which may be true (if unnatural), but the importance of ability lying outside the main system of modality is seen, for example, if we compare requests such as ‘Could you help me?‘, which is a neutral acknowledgement that you have the ability to help me, against ‘Would you help me?‘ which, being in the main system of modality, is asserting my opinion that you should help me.
Another classroom activity I use to introduce this difference is by drawing a squiggle on a piece of paper. We can then see who has the best imagination by making a list of what it possibly could be: a butterfly, a map, a doodle, etc. The point here is that it not our own personal opinion, we are merely making a list. Then, students can choose what they see as the best choice of what it might be, introducing personal responsibility for a decision. This activity can be adapted for business or higher level students with a role play activity discussing changes to an office building to make it more environmentally friendly by first listing the possible options (we could install double glazing) and then offering a personal assessment of that choice (it would save electricity, it might be expensive).