Essential question

Why adapted literature more useful for learning english than classic literature?

Is it provocative? Yes it is.Some people think that adapted books in English is "dry presentation" of the original work. In fact, this is not so. Indeed, such books contain fewer idioms, complex metaphors, vivid comparisons and specific terms. However, the plot remains the same, and the benefits of reading is not reduced! 

Is it open-ended?Yes it is. Some people believe that students should start by reading the original books, even if they have just started to learn English. In most cases, it is advised to read fairy tales, children's stories. However, I want to note that the literature for children can contain quite a lot of vocabulary, not the most necessary for everyday communication (all sorts of "Princess", "fairy", "magic wand"). 
And if they start with the classics? Unadapted works of William Shakespeare is not easy to understand even with the level of Upper-Intermediate. There are so many archaisms unused in modern English. 

Does it arise from real world dilemmas that students find interesting? Yes ,it does.Currently, most students work and don't have free time to read the original literature. Because the amount of information and work with the dictionary is large enough. Adapted literature is the way out. It helps to improve vocabulary, reading, as it includes tasks for the passed work. It is also a useful time saving.