The author uses “cosec” instead of the more standard “csc”. This can be confusing to the student. Also, there are advertisements throughout the lesson which can be distracting. Finally, in the examples page there are videos, but the videos are presented in a foreign language, which is strange since the rest of the lesson is all in English.
It is clear, by the flavor of English used, the material is aimed at learners whose first language is not English. This, in itself is only a concern for those who do not hold Hindi as a language in their domain.