How are DQ's handled by the coaches in practice?
If your swimmer is disqualified (DQ'd) in a specific event, it is because they broke one or more of the rules of the stroke, usually (but not always) in a way that gives them an advantage over the others swimming the stroke properly.
DQ slips are completed by the judges making the call. Two judges (one from each team) must agree *and* sign the slip for a swimmer to be DQ'd. If only one judge sees an infraction, that judge will complete and sign the slip and it will be recorded as a "warning*."
DQ and Warning slips are given to a representative on the swimmer's team after the meet, and from there to the Head Coach. The Head Coach and coaching staff review the DQ slips for their swimmers for feedback, and then attempt to work on these things with the swimmer during practice. Once the coaches are done with the DQ and Warning slips, they are filed in family folders; you are free to share them with your swimmer, or dispose of them as you see fit.
If you have a concern as to how your swimmer's DQ's are being followed up on in practice, please email or leave a note in a coach's file folder at the pool, or otherwise let them know that you would like to discuss. Also, please let a coach know if you don't get a DQ or Warning slip if you should get one.
* If your swimmer receives a warning slip, their time and swim stands/ is official. However, it should be seen as feedback that there may be more work to do to make that particular stroke "legal." Talk to the coaches if you have any concerns.