Recently Medical Associations, doctors and leading scientists have commented on the safety of mobile phones, wireless computers and other wireless transmitters in schools. I'm lucky that my children's school doesn't use wi-fi or allow mobile phones, but I know a lot of schools do.
The American Academy of Environmental Medicine in June said "Adverse health effects, such as learning disabilities, altered immune responses, headaches, etc. from wireless radio frequency fields do exist and are well documented in the scientific literature. Safer technology, such as using hard-wiring, must be seriously considered in schools for the safety of those susceptible individuals who may be affected by this phenomenon."
The Russian Committee responsible for protecting the public from non-ionizing radiation also called for schools in Russia not to use wi-fi in June 2012.
The Austrian Medical Association and International Society of Doctors for the Environment recommended that schools don't use wi-fi.
You might like to discuss this with your schools.