It is a good website to test students' grammar, also could be an extra practices for students. When I tutor students, I use this tools to be a grammar practice. We teach the grammar rules first, but students sometimes are confused the rules. If we give students extra practices, they will figure out the rules and be much more familiar with it.
This website help us as teachers to understand the rights of inmigrants when learning English as a second language because they have to be taught in a different way, due to their background and as English is not a first language for them. This article is related with job too, because inmigrants go to other places to learn a new language like English and have the opportunity to work in those places.