Mathigon is a great virtual manipulative opportunity that makes use of hands-on opportunities for students to enhance math knowledge.

Solveme Mobiles provide a great pre-introduction to.

These are all number talk images that you can use to have great discussions with students about how they counted, where they see the math, or provoke conversation.

Slow reveal graphs help students see trends in data digitally.  They are almost like doing mystery lessons with students and are very engaging.

Clothesline math is a great tool to help students with ordering and comparing.  It makes use of fractions, integers, functions and roots and exponents.

Mathies are another great virtual manipulative developed by the Ministry of Education.  

Estimation 180 is a terrific way to digitally show pictures and have students estimate and show their thinking.  Although there is a right answer you can just focus on the process and have students really dive into their thinking and reasoning.

Knowledgehook is a Canadian-based review site.  It is a terrific tool to review concepts with students and keep them engaged.  It is also ideal for teaching students how to take digital tests such as EQAO.

Equatio allows you to create mathematical equations, formulas, and more directly on your computer in Google Docs, Slides, PDF's or in a web app for other platforms.  It is an extension so you will need to add it to chrome for all students.  

Desmos is an interactive site that allows students the opportunity to explore a wide variety of math learning.  It provides student supports, teacher supports and works well with chromebooks.

The Math Learning Center creates resources. All apps are available in two or more versions: a web app for all modern browsers, and downloadable versions for specific operating systems and devices (such as Apple iOS for iPad).