As a native speaker and a high school English teacher, I am not sure this addresses the wide variety of dialects that are spoken in the language. Some of the examples that I saw in the level 1 one quiz were not inclusive of this. For instance, one question asks users to fill in the blank: “...why don’t you wash _____ the dishes.” This app states that the correct phrase is “wash up.” As a native speaker, I chose “wash off.” Both phrases are correct, but I would never use the first. On another question it asks: “you need to fill ____ a form.” Again, as a native speaker, my first instinct was to look for “out” in the answer choices. However, no such choice existed. This app states the correct phrase is “fill in.” Of course, this isn’t incorrect, but it does not consider the variety of ways of speaking within the language. I live within in the middle band of America, so my natural dialect is very generic. It’s not as if I live in Southern Alabama or Boston. I am giving the app 4 stars, though, because the app is still useful for someone who is trying to learn English on their own. I just wonder what someone who learned English from this app would think after being asked to “fill out a form” when they believe the correct phrase is “fill in a form.” How would one then fill OUT a form? See my issue with it?