Dear Teacher,

Here are some of the most useful sites I've found for teaching and learning mathematics. I've limited the links to things I use frequently or find invaluable as a resource in my teaching.

Daniel Shadock

My two cents.

General Teacher Links

Edmodo This outstanding free site allows you to easily communicate with your students and parents, as well as, give quizzes, polls, and collect assignments. It takes a little experimentation to figure out all the features, but it is a resource I now use every day.
Kahoot This site lets you create, or just use one of the many already created, online multiple choice quizzes which the entire class plays simultaneously. It keeps track of who is leading after each question, plays trivia music, and shows a countdown timer for each question. Conveniently, if another teacher has created a quiz that almost fits your topic, you can make a copy and modify it to meet your students needs. It requires wifi in the classroom, but students can play on smartphones, tablets, or computers. Students login here.
Engrade This free, professional, online gradeboook resource is the best out there. It is simple to use and elegantly organized. Even compared to other expensive gradebook programs I've used, Engrade comes out on top.
Padlet This is a free digital collaboration tool which allows a teacher to project a question or statement for the class, then have students simulataneously attach sticky notes or pictures to the digital bulletin board using any device. This is a convenient way to collect exit slips.
Print Free Graph Paper A useful resource if you have trouble obtaining graph paper. It has adjustable paper and grid sizes, as well as the option to print polar and logarithmic graph paper.
Clip Converter Free site which allows you download YouTube and other online media as MP3, MP4, WMV, or several other file options. Great if you don't have internet in the classroom.
Organizing Your Digital Self This is a great page on organizing everything digital by Maria H. Anderson at the Muskegon Community College. Her page also has some useful classroom resources

Math & Teacher Blogs

Continuous Everywhere but Differentiable Nowhere Sam Shah is an innovative math teacher in Brooklyn, NY who has created a great site with lots of useful ideas.
Building our Classroom This is a well organized site with an enormous amount of info on the practical side of teaching. It has useful ideas for new and veteran teachers alike.
Kathy Schrock's Guide to Everything This isn't exactly a guide to everything, but it is a comprehensive guide to using technology and the internet in classroom. It is an exceptional site, which is extremely well organized. My favorite section is the Infographics as a Creative Assessment.
Math Teacher Wiki This site has some great material, but I find much of it to be limited use. Still, it has enough good stuff to be worth a look.

Below are some resources on additional topics in mathematics, as well as links to challenging problem sets.

Other Resources

Cut the Knot This terrific site is full of interactive mathematics miscellany and puzzles. One of my favorite math sites on the internet.
ABC News "Who's Counting?" Great column by ABC news which focuses on the mathematics of current events. Helpful in understanding the role of mathematics in understanding the modern world.
Mathematics Library This Drexel University's Mathematics Library with organized links to what seems like nearly every mathematics site on the internet.
History of Mathematics This University of St. Andrews site has essays on the history of mathematics organized by culture, as well as a brief cronological overview.