I have to agree with Manapa. The breath is an excellent object. Not only is it natural and readily available, the breath is both intimately connected with the body and the mind. Note how our breath changes with changes in our mental state. When we get angry, our breath becomes short, fast and sharp, when relaxed - slow and smooth, etc.
As your partner suffers from ADD, I recommend that he uses the samatha variant of anapana-sati which is to remain continuously mindful of the touch of the breath (around the nostrils and below the upper lip) for longer and longer periods. This will help to develop calm (samatha) and concentration (samadhi).
“No lists of things to be done. The day providential to itself. The hour. There is no later. This is later. All things of grace and beauty such that one holds them to one's heart have a common provenance in pain. Their birth in grief and ashes.”
- Cormac McCarthy, The Road
Learn this from the waters:
in mountain clefts and chasms,
loud gush the streamlets,
but great rivers flow silently.
- Sutta Nipata 3.725
(Buddhist aid in Myanmar) • •