The U.K.'s far right is often emboldened after attacks inspired by militant groups like ISIS.
Theresa May launched an inquiry to ensure Sharia court principles were compatible with British law.
British Muslim women face sexism, discrimination, and economic disadvantage.
Channel 4 documentary, What British Muslims Really Think, will air on Wednesday
The boy had intended to write that he lived in a "terraced" house but his teachers called the police.
The hashtag has been used more than 60,000 times since Saturday night.
A letter signed by a range of community leaders condemns the "ongoing demonisation of Muslims in Britain".