If things are going well, tell her. We all like thanks for a job well done. Offer help, suggestions, and materials when appropriate. If a problem or concern arises, make an appointment to discuss it. It is hard to talk at pickup time.
Children are weary and hungry.
Other parents need the provider's attention too. Perhaps an evening phone call will give you the privacy and time to solve the problem. Visit with your child about his day's activities on the way home, as you fix dinner, and other routine times during the evening. Let him know you think about him during the day. Have a bedtime routine of reading a story and talking about the day's happenings.