Absurd Math: Pre-Algebra from Another Dimension is an interactive mathematical problem solving game series. The player proceeds on missions in a strange world where the ultimate power consists of mathematical skill and knowledge. Many of the pages have hidden clues and areas. Players, teachers and parents may email for assistance and answer keys.

MathStar introduces students to addition and subtraction of integers.  Interactive elements are supported by video clips, worksheets, teacher guides, a glossary, and standards correlations.

Interactives provide a real-time connection between representations of the mathematics (symbolic, graphical, etc.), so that changes in one representation instantly cause changes in the other. Created by the Concord Consortium, they were designed as part of a teacher professional development program and are free for public use.

“Survivor Algebra”, a cooperative learning activity, is spelled out in detail in the teacher’s section of Cool Math, complete with tips on classroom management. The student section offers study tips, online graphing calculators, practice and review problems.

Students can plug in problems that cause them difficulty at Webmath.com. They receive an instant solution along with a step-by-step explanation of how the problem was solved, or a reason why the problem could not be solved with the information provided. Computer-generated responses are clear and easy to follow.

This site contains Java applets that interactively explore topics in pre-calculus such as quadratic, rational, exponential, logarithmic, trigonometric, polynomial, absolute value functions and their graphs. These tutorials can be used either as complements to topics already studied or to learn a new topic through exploration.

Math.com provides step-by-step tutorials for middle (Pre-Algebra) and High School (Algebra) students requiring targeted assistance or remediation.

High School

Geometry Problem of the Week from the Math Forum features eight years' worth of geometry problems, with comments and student solutions.

Geometry 3D Shapes is an interactive lesson from the Annenberg Foundation that lets students explore shapes and their methematical properties.

Understanding Ratios of Areas of Inscribed Figures from the National Council of Teachers of Mathematics (NCTM) lets students explore the relationship between the areas of a polygon and an inscribed figure formed by joining the midpoints of the polygon's consecutive sides. (Linked to grades 9-12 geometry standards; teacher materials provided.)

The Mathematics of Rainbows from the University of Minnesota is on online lab that helps students understand geometric properties of rainbows by exploring the laws of reflection and refraction. It also enables students to experimentally determine the angle at which rainbows appear in the sky.

Euclid's Elements is an online version of the classic text from Professor David Joyce at Clark University. All figures are illustrated using Joyce's Geometry Aplet, an interactive program that lets users manipulate them by dragging points in the figure diagrams.

Interactive Mathematics Online is a student-created Web site with sections on geometry, algebra, trigonometry, and chaos theory.

The Fractory provides an explanation of what fractals are and how they are created. Developed by students, the site also allows users to create fractals of their own.

Fractals: An Introductory Lesson explores fractal mathematics with several small, interactive programs for hands-on construction of and interaction with simple fractals. Teachers using the site can request a password that allows students to open "answer boxes" only after they have worked the solutions themselves.

Geometry from the Land of the Incas is a Peruvian site which uses proofs, animation and sound to explore Euclidean geometry problems involving circles and triangles. Students can also investigate how geometric principles were used at ancient cities such as Cuzco, Machu Picchu, or the Nazca Lines.

Middle School

Fun Mathematics Lessons from Cynthia Lanius include Rectangle Pattern Challenges, Geometry Online, Fractals, Dueling Pinwheels, Polyominoes, and more.

Learning about Length, Perimeter, Area, and Volume from NCTM uses interactive figures and dynamically generated graphs to help students learn about geometric relationships among similar objects. (Linked to grades 6-8 geometry standards; teacher materials provided.)

Understanding Congruence, Similarity, and Symmetry Using Transformations from NCTM lets students manipulate a shape and observe its behavior under a single transformation or a combination of transformations. (Linked to grades 6-8 geometry standards; teacher materials provided.)

Understanding the Pythagorean Relationship from NCTM features an interactive figure that helps students understand this relationship and gain experience with transformations that preserve area but not shape. (Linked to grades 6-8 geometry standards; teacher materials provided.)

The Mysterious Tangram Game provides several interactive tangrams for students to solve online.

Different Views of Solids from Harcourt e-Lab presents a visual exercise in which students can slice solids to make congruent plane figures.

The Pythagorean Theorem offers hints that help students discover the theorem on their own as they go through the online lesson.

Geometer's Sketchpad Classroom Resources from the Math Forum provides lessons, ideas, problems, and downloads for Sketchpad users.

Figure This! from NCTM presents mathematics challenges for families. Click on Math Index to find geometry challenges.

Math in Daily Life: Home Decorating from the Annenberg/CPB Project illustrates practical uses of geometry.

BrainBinders are puzzles that can be printed out and folded to create a particular shape.