Introducing this concept can be really challenging for parents and or teachers with little experience. I have posted a resource which allows that wall to break. It took about three years to construct that perfect resource but it works!
Few key things to remember
Modify with each class/student as you see necessary. i.e make harder, longer, easier.
Prior Knowledge : Integers or Directed Number and Linear Relationships , Algebra techniques 2 (NSW Syllabus) also Patterns and Algebra from stage 3 is an advantage!