Gizmos at Explorelearning
http://www.explorelearning.com/

ExploreLearning Gizmos, the world's largest library of interactive online simulations for math and science education in grades 312.
They even offer a free one month trial.

Illuminations (National Council for Teachers of Mathematics)
http://illuminations.nctm.org/

Illuminations is designed to: · provide standardsbased resources that improve the teaching and learning of mathematics for all students. · provide materials that illuminate the vision for school mathematics set forth in Principles and Standards for School Mathematics, Curriculum Focal Points for Prekindergarten through Grade 8 Mathematics, and Focus in High School Mathematics: Reasoning and Sense Making.

National Library of Virtual Manipulatives
http://nlvm.usu.edu/

The National Library of Virtual Manipulatives (NLVM) is an NSF supported project that began in 1999 to develop a library of uniquely interactive, webbased virtual manipulatives or concept tutorials, mostly in the form of Java applets, for mathematics instruction (K12 emphasis). The NLVM is a resource from which teachers may freely draw to enrich their mathematics classrooms.

BrainPOP
http://www.brainpop.com/

BrainPOP® creates animated, curricular content that engages students, supports educators, and bolsters achievement. In traditional, blended, and "flipped" learning settings, BrainPOP supports individual, team, and wholeclass learning. At school and in informal learning environments, our characters help introduce new topics and illustrate complex concepts.

Figure This! Math Challenges for Families.
http://www.figurethis.org/challenges/math_index.htm
http://www.figurethis.org/fc/family_corner.htm

Figure This! provides interesting mathematical challenges for families of middle school students that can do at home with their families. Solutions are provided.

CLIPSCritical Learning Instructional Paths Supports in Mathematics
http://mathclips.ca

Interactive curriculumbased mathematics activities for grades 7 – 12.

epractice Grades 4 – 8
SWF Download Table http://www.oame.on.ca/GapClosing/
http://oame.on.ca/clips/index.html?ePractice=T&oneCluster=101

ePractice activities are interactive webbased opportunities for students to build confidence in their understanding of concepts and skills. This release focuses on Representing Fractions for the Junior and Intermediate Divisions. Each activity aligns with a particular Gap Closing lesson.

Homework help
https://homeworkhelp.ilc.org

Homework Help  Math help for grades 7 – 10
Click on “Register” to get started and follow the instructions online. Click on “Register” to complete the registration process Note: Students need their OEN – Ontario Education Number to register.

Nelson Mathematics Companion Site
www.nelson.com/math/companion.html

Activities and quizzes to support secondary school mathematics

Nrich  Mathematical Games and Problems
http://nrich.maths.org/public/index.php

Enrichment mathematics activities and challenges for students in grades 1 – 12

Esso Family Math
http://www.edu.uwo.ca/essofamilymath/

Helps parents and children share their thinking and understanding of math in a safe and relaxed atmosphere…home! Resources reflect Ontario’s curriculum.

University of Waterloo Mathematics Activities
http://cemc.math.uwaterloo.ca/resources/potw.php
http://cemc2.math.uwaterloo.ca/wired_math/index.html

Problem of the Week (Grades 5/6/7/8, 9/10, 11/12): Students can engage in solving mathematical problems each week. Teachers may sign up to receive emails which contain these weekly problems.
Wired Mathematics (Grades 710): Students, teachers, parents and tutors may access games, lessons, challenges and enrichment activities on this website.

IXL Learning
www.IXL.com

Users can try out their practice activities freely for a timed session before being asked to join the site. IXL makes math practice fun! IXL allows parents to monitor the progress of their children and motivate them through interactive games and practice.

Khan Academy
www.Khanacademy.org

On this site you will find a library of over 2,400 videos covering mathematics to physics, finance, and history.

Math Gains’
The Geometer’s Sketchpad Applets
http://www.edugains.ca/newsite/math2/applets.html

On this site you will find readymade Geometer’s Sketchpad files (grades 712) for you to explore. To open these files you will need version 4.07 “Geometer’s Sketchpad” or higher.

WolframAlpha computational knowledge engine
http://www.wolframalpha.com/

Use this site to obtain information on a variety of topics, e.g., do math, search out facts, find definitions of words, etc.

XtraMath is a nonprofit organization dedicated to math achievement for all. Their goal is to develop effective, efficient, adaptive, and intrinsically rewarding supplemental math activities.
https://xtramath.org/#/home/index
 The website's goal is to develop effective, efficient, adaptive, and intrinsically rewarding supplemental math activities. 
Open Middle http://www.openmiddle.com/  Most of the problems on this site have: a “closed beginning” meaning that they all start with the same initial problem.
 a “closed end” meaning that they all end with the same answer.
 an “open middle” meaning that there are multiple ways to approach and ultimately solve the problem.
Open middle problems generally require a higher Depth of Knowledge than most problems that assess procedural and conceptual understanding. 
Math Snacks https://mathsnacks.com/
 Smart educational animations, games, and interactive tools that help midschool learners better understand math concepts Students engaged in Math Snacks in class learned more math than those with access to just classroom instruction. 