I guess the problem is that, while technically accurate English, it’s a pretty non-standard usage. One sees a page full of a variety of planes and it’s expected that the following text will make a general statement on planes as an idea: There are so many kinds of planes!
To refer to a group as the book does, it’s just kind of clunky and awkward, and on top of that so many kinds is, in my experience, just an unusual adjective form. Teaching children how to read isn’t just about learning how to sound out words: it’s also about how to suss out their meaning, and a child at this reading level may have a hard time understanding the more abstract grammatical form that this book decided to take.
I guess the problem is that, while technically accurate English, it’s a pretty non-standard usage. One sees a page full of a variety of planes and it’s expected that the following text will make a general statement on planes as an idea: There are so many kinds of planes!
To refer to a group as the book does, it’s just kind of clunky and awkward, and on top of that so many kinds is, in my experience, just an unusual adjective form. Teaching children how to read isn’t just about learning how to sound out words: it’s also about how to suss out their meaning, and a child at this reading level may have a hard time understanding the more abstract grammatical form that this book decided to take.