I agree with JohnT, get him to find his own work experience placement.
I look at work experience as the total picture - from search, to apply to interview (maybe no more than arriving at the premises with a form to fill out ) to the actual week on the job.
I had my own business for 13 years (retail) and always had work experience kids. Also looked after work experience kids as an employee (in the electronics repair industry) for many years prior to that. I always requested the applicant bring the form to us before committing to taking them on. This effectively created a 2 minute interview. The standard of presentation, dress, attitude and interest portrayed by the kids often was appalling and earned then a "sorry, already have a work experience person that week (we only could take one at a time), even if this were not true. Working in retail, and in a busy large retail center, first approach by customers to staff (even if on work experience) was very important to the overall presentation of the shop.
The ones that seem to get the most out of it are those who generally wanted to experience working in the area. Those "mothered" by their parents making the approach and dragging them along (or bringing them under their wing - literally) to get their application form filled out never seemed to be as keen or interested as those who did the groundwork themselves.
Those who applied for "anything" because they HAD to find SOMETHING to start "next week" (because they just could not be bothered to get off their bums and search for their likes in a timely manner) were always a mixed bunch. - Well at least I suppose they did search, apply, attend and do the groundwork eventually, so they must have got some insight into the job hunting phase of work experience.
I always held the view that it was work "experience", so went out of my way to "put them to work" (menial tasks often - but what can you teach a teenager in a week!?), but most appreciated the experience. We never got them to do something we would not do ourselves ( and told them this would be the case before they started), and I insisted on staff doing the same tasks at the some time (between serving)
Best kids were those who already had - or did have in the past, a part time position, usually at a fast food outlet. These kids brought with them the ethos of working and understood what commitment, dedication to task and just general "working" was all about. Highly recommended if you can get your son to take up a part-time job.