Want to learn more? These websites may help guide you in the right direction:
http://www.worrywisekids.org Worry Wise Kids provides some of the most comprehensive and thorough information regarding childhood anxiety disorders. From descriptions to "red flags", from strategies to treatments, Worry Wise Kids is a wonderful resource for parents and teachers a like. What Worry Wise Kids provides that most websites do not, is under the "at school" tab on the left, they include a section on children's rights and IEPs.
http://www.childmind.org/en/anxiety/home/ Child Mind takes a more psychological approach to presenting information, but it is extremely user-friendly and easy to comprehend. Each disorder is broken down into descriptions, causes, diagnosis, signs, symptoms, etc. At the bottom of each "quick facts" page, users can find links to a more detailed page, and various links regarding the disorder.
http://www.selectivemutism.org/about-smg/what-is-sm Selective mutism is a tricky, more complicated disorder in the same family as social anxiety that is far more debilitating. SMG provides detailed information regarding the confusing disorder, and gives more support than other websites. From documentaries to a FAQ page, SMG provides an easy to navigate and easy to understand resource.
http://www.adaa.org/understanding-anxiety The Anxiety and Depression Association of America's website provides one of the most detailed and specific resources for information regarding anxiety disorders (especially in children, there are separate pages for children and adults). Not only does it provide information, it provides help resources as well, which can be beneficial for families who are just starting their mental health journey.
http://www.nimh.nih.gov/health/topics/index.shtml The National Institute of Mental Health is a government organization dedicated to providing information and outreach regarding mental health. From statistics (both adult and children) to detailed information pages laden with details regarding symptoms, treatments, diagnosis, and current scientific research (and updated developments!), the NIMH website offers an easy to navigate, and user friendly source of reliable information.