Use floss
Floss is two hurdles in one: the thread has to slide between tight teeth, and the gums often bleed a little the first few nights. The pictures below remove the guesswork on grip and order, so the habit gets time to set in.
♂Use floss
A person uses floss to clean their teeth.
About this visual support
Flossing is the dental habit most families drop, and laziness is rarely the real reason. It is two obstacles at once: the thread has to slide between teeth that sit close together, and the grip needs both hands to hold it taut in a way that feels clumsy at first. Add a little blood on the gums during the first nights, and the whole exercise reads as a stop sign.
A picture sequence gives the child a plan instead of a puzzle. Tear off about forty centimetres, wrap around the middle fingers, leave a short section in between, slide between two teeth, curve it into a C against one tooth and pull gently up and down. Then on to the next gap, same shape. Once the hands know the move, it stops being a concentration task and turns into a quick habit.
Practical tip: start with floss picks for a week or two before switching to the string. They are clunky, but they only need one hand and remove the early frustration. In Routined you can place floss as its own step in the evening routine, so it does not get folded into brushing and quietly forgotten.