Please visit the Help by Subject area for dozens of pages of links to lesson plans, educational websites, and other resources organized by subject. The links below take you to websites that also offer lesson plans and worksheets but you will have to do your own searching from their homepages for specific topics.
Founded by Salmon Khan based on his experience tutoring his nephew online, Khan Academy is perhaps the largest free online learning resource in the world. It offers a large college admissions section in addition to the learning resources.
The site offers free lesson plans and activities (indexed by grade level and topic) that tie into PBS educational programming. You can subscribe to an email newsletter and get tips on upcoming PBS programs that might be of interest for your family.
KidsDiscover is a popular educational magazine with each issue dedicated to a specific topic. The website offers teachers teacher's guides and power vocabulary guides for dozens of topics.
edX is an online open courseware provider founded by Harvard and MIT in 2012. Most courses are self-paced and currently available; some are upcoming or archived. The courses are usually free to take with an option fee for a verified certificate.
The Learning Network offers lesson plans, writing prompts, contests, critical thinking exercises, and more based on content from the NY Times. Start with "How to Use This Site" to make the most of the resources offered.
"CNN 10 replaces CNN Student News, the network's longest-running show that first aired in 1989. CNN 10 more effectively serves a growing audience interested in compact on-demand news broadcasts ideal for explanation seekers on the go or in the classroom. The show's priority is to identify stories of international significance and then clearly describe why they're making news, who is affected, and how the events fit into a complex, international society."
LessonPlanz.com is searchable directory of free online lesson plans and lesson plan resources for all grades and subjects.
Free lesson plans by topic
Huge site with links to almost every conceivable topic
Large collection of resources used by Mr. Donn in his classroom