My wife has recently taken a big interest in trap shooting. She's strictly a beginner and has been shooting with me for about a year. Thus far her actions have been excellent with respect to learning safety etiquette. Then came the day... We were shooting trap and my wife was at her station and I was standing behind her off to her right. My wife is a guest at my gun club and per the rules we can't both shoot at the same time. I need to be in control of her at all times. This was only her 3rd outing shooting trap. The AD unfolded as she took position at the middle station (which is the easiest to shoot ), she then chambered a round, and then I asked if she wanted to move to a different station. She replied yes, she then attempted to thumb the safety to "safe" and BANG the chambered round went off.. luckily the gun was pointed downrange and into the dirt. My wife uses a Mossberg 9200 which uses a very stubborn stiff moving thumb style safety. We recreated why the AD happened and #1 was the fact she had her finger inside the trigger housing and was simultaneously trying to thumb the stubborn safety button to safe. I also take partial blame as I was not paying 100% attention to the fact she had a chambered round and I then asked her to move to a different station. I should have just waited to let her shoot, verify the gun was cleared/safe THEN allow her to move. So the two lessons learned, always keep your finger out of the trigger housing until on target, and as teachers do NOT let yourself be distracted by your new students firearms handling tasks.