What is the ruling regarding girls who falsely claim to be menstruating to avoid communal prayer at school, then pray secretly when their actual menstrual period comes, for fear of exposure?

This action is not permissible due to the falsehood involved in feigning an excuse, abandoning or delaying prayer, and praying during menstruation. They must be advised and reminded of the sin of lying and the punishment for delaying prayer, as Allah Almighty says: "Who are heedless of their prayers." (Qur’an 107:5). And whoever is found to delay prayer or pray while menstruating must be punished in a way that prevents her from repeating it.