Online Resources (for everyone)

AIMS Puzzle Corner
A collection of puzzles and brainteasers.

SAT Preparation Center
The official math SAT practice questions and information.

MacTutor History of Mathematics Archive
Biographies of mathematicians and essays on the history of mathematics.

Dr. Math
Answers to common and uncommon questions about math.

Chaos Under Control
Small downloadable applications related to chaos and fractals, such as cellular automata and the Mandelbrot set.

Online Resources (more advanced)

Sage Computer Algebra System
Downloadable software with a wide range of mathematical functions.

Wolfram MathWorld
An extensive encyclopedia of mathematics.

Online Encyclopedia of Integer Sequences (OEIS)
Searchable database of sequences with commentary.

Proof Explorer
A database of formal proofs of many mathematical theorems.

Great Math Organizations in New York City

The New York Math Circle
Math enrichment for middle and high schoolers.

The School of Mathematics
Open-ended exploration of mathematical topics, free and open to all.

Math in the City
Professional development and curriculum think-tank.

Great Math Organizations outside New York City

The Algebra Project
A community organizing, teacher training, and curriculum development organization devoted to equality of opportunity in math education.

The Math Circle
A program of courses for students aged 5 through high school age.

Math Solutions
An organization devoted to the professional development of mathematics teachers.