Women giving a false excuse for not praying
Question

                In some schools the girls are obliged to pray in jamaa’ah and they allow the girls who have their period to sit in a special place. Some of the girls – may Allaah guide them – tells lies to the supervisors and claim that they have their period, and so they do not pray for as long as a period would normally last, then when their period really does come they stand and pray with the others, fearing that they will be caught out. What is the ruling in their case? Please explain.
Praise be to Allah.
    What they are doing is not permissible, firstly because it is 
    an obvious lie by which they are claiming to have an excuse. Secondly, they 
    are failing to pray, whether they are not praying at all, or they are 
    delaying the prayer until after the proper time, or failing to pray with the 
    congregation of women. Thirdly, they are praying after that, at the time 
    when they really do have their period. You have to advise them, remind them, 
    exhort them, and explain to them the sin of lying and the punishment for 
    delaying the prayer beyond the proper time, because Allaah says 
    (interpretation of the meaning):

    “So woe unto those performers of 
    Salaah (prayers) (hypocrites),

    Those who delay their Salaah (prayer from their stated 
    fixed times)”

    [al-Maa’oon 107:5]

     Any girl who is found out to have delayed her prayer and 
    prayed when she was menstruating should be punished in a manner that will 
    deter her and make her give up these actions which are denounced by Islam. 
    And Allaah knows best.