Learning Express: These practice sets, tutorials, and eBooks will help middle school students learn and review important math skills, so they can do their best in class, on tests, and while preparing for high school
TED Ed: Pixar: The Math Behind the Movies
Steven Strogatz on the Elements of Math: Steven Strogatz, an award-winning professor, takes readers from the basics to the baffling in a 15-part series on mathematics. Beginning with a column on why numbers are helpful, he goes on to investigate topics including negative numbers, calculus and group theory, finishing with the mysteries of infinity.
High school math site. Click on "Maths" in the left-hand tab
Middle school math site. Games for math class that have kinesthetic components. Scroll past the first few pages to get to the good stuff....
University of Cambridge Maths and Sport Articles
ISEF Student Research Categories
AMS: Research Projects for Students
MATHEMATICS RESEARCH PROJECT IDEAS SUITABLE FOR HIGH SCHOOL AND COLLEGE STUDENTS
Contemporary mathematics research ideas from the Institute of Mathematics and its applications.
Math projects for Science Fairs
POSTERS: A seiries of posters that promote appreciation and understanding of the role mathematics placy in science, nature, technology, and human culture.
Annenburg Learner: Support lessons for numbers, algebra, trigonometry, calculus, geometry, physics, and statistics with additional lessons on math history.