Well, play with him yea.. but it's no use if they don't know the basic rules. I remember when my grandma was over for a bit and i asked her if she wanted to play chess. She didn't actually know how herself and i was pretty much doing her moves. Not much fun for either of us i guess. But that's on the other side of the scale and probaly not much help to the situation..
If your going to teach him, make sure you teach him the right rules too. It gets a bit annoying if he goes to play chess with his mates and people don't know which rules are correct. I didn't find chess books very helpful, but probaly because i wasn't really a beginner when i read the. I think the best approach is you telling him what each piece does and then play with him, giving him hints on how to play and let him work on from there. Having a novelty chess board helps too. (Although i wouldn't recommend the drinking one
)