Is it permissible for a menstruating woman to feign prayer in front of her children to accustom them to it, especially since they inquire about the reason for her not praying?

There is no need for a menstruating woman to pretend to perform ablution and prayer, as she is forbidden from prayer and ritual purity. It is advisable for the wife to occupy herself with something else during prayer times to avoid questions from children. There is no religious impediment to merely standing and bowing without intention or recitation, nor to washing the parts of ablution without intention. It is not required to accustom children to prayer before the age of seven, as the Sunnah begins at seven years of age, but there is no objection to accustoming and encouraging them to it. The priority at this age is to teach them supplications and virtuous manners.