Mosquito Devices!!
http://ning.it/I0TBsW

Canada: BCCLA calls on School Board to throw out rights violating devices
The B.C. Civil Liberties Association is insisting that the Vancouver School Board remove 33 “Mosquito” noise devices that target children from schools across the city. The devices emit a loud and painful sound frequency only audible to young people, toddlers and babies. They are often used to keep young people away from a particular property, but still permit access to adults.

“These devices have been found by the European Union to be a violation of the United Nations Convention on the Rights of the Child,” said Robert Holmes, Q.C., President of the BCCLA. “A teacher would not be permitted to cause pain or discomfort to a child for punishment; why should our schools be permitted to do the same to deter youth from gathering?”
Read more at link, includes a letter to the Vancouver School Board