Children are children. But no sooner especially the girls, when body shapes become noticeable abd recognisable, then the order of "baligh" girls apply to them and when water touches the clothing then extra caution must be taken. For near baligh girls and boys to be in one pool, even in small numbers is against the Shariat.
"Hayaa" (shyness, modesty) is of vital importance for every Muslim. The causes leading to sin cannot be opened for any reason.
