Education association websites are great resources for free articles, reports and other material. Some associations provide content free of charge, while others require you to be a member. Below are some education associations you might consider joining. There are many others that you can find through Google.
AERA, founded in 1916, is concerned with improving the educational process by encouraging scholarly inquiry related to education and evaluation and, by promoting the dissemination and practical application of research results.
National association is for those working in public education.
IRA is a professional organization for reading teachers. It also publishes several prominent reading journals, such as The Reading Teacher and Reading Research Quarterly.
NCTM is an association for math teachers. Teaching Children Mathematics, Mathematics Teacher and other math journals are published by this organization.
This website contains a good deal of free content from the preeminent association for science teachers.
Besides providing access to recent educational resources, professional organizations give you opportunity to network, or meet with other people in your profession. Networking can provide you with job leads and help you keep abreast of developments in your field.