A school district in the US state of Virginia has closed all schools on Friday after a geography lesson that included Islam sparked vociferous complaints from around the country.
Students were asked to trace Arabic calligraphy in an exercise some parents said amounted to indoctrination.
Officials said the schools were closed out of an "abundance of caution" and there were no specific safety threats.
School administrators say a different lesson will be used in the future.
One week ago, students at Riverheads High School were studying the Middle East and were asked to trace a piece of Arabic calligraphy that translated to: "There is no God but Allah and Muhammad is the messenger of Allah".
Some pupils refused the assignment and parents accused the teacher of indoctrination.