I checked one of the spelling tests and can understand why many students (and adults) would get the words wrong. They testing is typically for the trickier words. Isn't it interesting that we focus so much on the trickier words, which often we can work around, rather than the majority of the words we use can spelling easily.
This made me wonder if there may be spelling mistakes on the NAP site and whilst generally it is very good, yes the site does have spelling mistakes. Here's an example of one which is a fairly common spelling mistake. There were others, but not a great number.
The article which I initially received and read made a very interesting point about the written test which was about the set time to write an article. When in our lives do we have to sit and write a document at a given time, for a given time period. It simply doesn't happen outside of the school system, or at least it hasn't happened in my career. Isn't it interesting the pressure we put our children under which is totally different from the world they'll be in when they leave school.
Creator of the preferred Australian English spelling dictionary.