No tax revenues of the State, or of any political subdivision thereof, or of any school district, shall be used for the free public education of pupils living in the State on real property exempt from taxes levied on real property. The limitations of this section shall not apply to pupils living on real property owned by the State or any of its political subdivisions, or by the federal government where such real property is used for nonmilitary housing, or where such real estate is exempt from such taxes on account of the use of such property for charitable, educational or religious purposes.