Hi Wilson,
You might think they know but in reality they might not know that well. Also, even knowing is not enough as we need them to practice. There is always factors from the emergency that hinder adequate behaviours and always a pourcentage of the affected population that does not practice, maybe because they lost their asset/handwashing supplies and handwashing becomes often a deprioritized activity when the emergency strikes. I would therefore recommend a quick assessment to confirm your initial thoughts and to confirm noone is left behind.