Introduction
There are many opinions on the way math is taught in schools and many teachers, tutors and parents have reached out for different or supplemental resources to help them take their children's performance in mathematics to a level that will open doors for them in future education and employment. Jump Math is a non-profit organization that has developed curricula and professional development that is intended to increase student success with math.
Purpose
Jump math offers a full curriculum that are consistent with the Ontario (and other regions) curriculum requirements which may be of use to schools if they are looking to adopt this approach completely. My experience has been limited in scope to using some of their materials for tutoring purposes. They provide assessment and practice books for grades 1-8 and they can be purchased in small quantities if you're not buying for a whole school.
Relevance
They offer some free samples (https://jumpmath.org/jump/en/learn) for all grades so you can get a good feeling for what the materials look like and how to use them. With the free samples, you can put them into a real-life practice with students to see how the materials perform in your specific context. In my limited experience, they were a great resource for assessment and practice. I would still sometimes pause in my usage of the materials and work with other materials to drill down deeper into a specific area or into a tangent area that I thought was enlightening for the student but I found them to be a very useful resource and a good foundation for the lessons I was delivering.
These tools are probably best suited for Assessment for Learning and Assessment as Learning.
Reliability
Jump Math is in use in schools in Canada, the USA and other countries. It is currently the subject of a study by the University of Toronto that is attempting to confirm a previous study's findings about the development of students learning using the Jump method.
Limitations
I haven't identified any specific limitations with this resource but there is a learning curve associated with becoming familiar with the materials and understanding how they should be used. That said, the free samples mentioned above give you an easy entry point to starting to use the materials and evaluate them for yourself.