Free online proofreading.

A collection of free digital resources.

Great archive of NPR's Weekend Edition "Math Guy".  Broad range of topics - could be a great supplement to class instruction.

Extremely large collection of e-Textbooks  -  customizable, free, curriculum-aligned content for K-12

"BioInteractive is a site from the Howard Hughes Medical Institute (HHMI) that provides free resources for science teachers and students. The site has videos, lectures, animations, links, downloads, lesson ideas, virtual labs and much more. You can even order DVD's of many of their programs for free. The virtual labs include: Transgenic Fly, Cardiology, Bacteria, Neurophysiology, and Immunology. The materials were developed by educators and scientists and are excellent."

Create poll, share link, done. No registration needed to create a poll - a very quick and easy way to gather feedback.

"This archive is designed as a resource for enriching your math courses and nurturing your interest and talent in mathematics! Each Math Fun Fact is a math puzzle or short article that contains a cool mathematics idea. You'll can learn about the mathematics of things like card shuffling to poker to computer vision to fractals to music, just to name a few. This makes great enrichment material for gifted math students or problem-solving groups."

This is a nice collection of math and logic puzzles.  Some familiar classics as well as some not so well-known.

GoldenNumber.Net exists to share information on the pervasive appearance of Phi, 1.618 ... ,  the Golden Ratio in life and the universe.  Its goal is to present a broad sampling of phi related topics in an engaging and easy-to-understand format and to provide an online community in which new findings about Phi can be shared.  Select an area of interest below or begin with Phi for NeoPhites or the Golden Ratio Overview article.  Enjoy the 'phi-nomenon'!

Solving a linear equation system of up to 20 unknowns.

math visualizations

"The National Science Foundation's International Science & Engineering Visualization Challenge annually recognizes individuals and organizations who produce educational graphics. There are five award categories; videos, interactive games, informational posters and graphics, illustrations, and photography. The awards recognize outstanding visualizations that can help educate students about complex topics in science. "

"Watch free documentaries online! Full videos are available! Educate yourself with thousands of good documentaries about diverse subjects." 

Gooru is a new service that aims to provide teachers and students with an extensive collection of videos, interactive displays, documents, diagrams, and quizzes for learning about topics in math and science. As a Gooru member you have access to hundreds of resources according to subject areas such as chemistry, biology, ecology, algebra, calculus, and more. Within each subject area you can look for resources according to media type such as video, interactive display, slides, text, and lesson plans. When you find resources that you want to use, drag them to the resources folder within your account. Gooru also offers you the option to add resources to your folders even if you did not find them within Gooru"

"Announcify is a free text to speech application that is available as a Chrome browser extension and as an Android app. With Announcify installed in your browser any time you're viewing a webpage you can simply click on the Announcify icon in your browser and have that page read to you. "