DS1 had his first check-up last week and his dentist says that because his teeth are quite close together he is getting food caught in them and she asked me to floss them

Has anyone else ever flossed a 6 year old's teeth? I'm afraid I was a bit too dumbfounded by the concept of having to floss his chompers to ask and intelligent questions. Such as....... is it better to use the tape that I use or should I buy those ones on a stick? Is it reasonable to think I can teach him to do it himself at his age or will I need to wait a year or 2?