Humanities Homework Help

I’m working on a english question and need an explanation and answer to help me learn.

We have studied the diagram on page 23 from the paper titled The Collection of the Quran by Harald Motzki as an illustration of his method for dating the hadith on the event of the collection. Describe in detail (step by step) how Motzki dates the hadith using it’s isnad (chain of transmission) and matn(textual content). When answering this question assume your audience is someone who haven’t studied this method before. 

One can appreciate the ingenuity of Motzki’s in devising the method above once it is understood. Explain in detail what compelled him to introduce this method?