Please read, very carefully, the "Foreword", also called the "Proem" -- the short, introductory pages before the beginning of "Day One, Tale (also called 'Novel') One."
Then, please read, very carefully, the part of "Day One, Tale One," that precedes the actual story of Ser Chiappelletto ("First Tale").
These two readings give the essential background for the rest of the Decameron.
Finally, study carefully Day Two, Tale Five -- Andreuccio da Perugia. What patterns do you discern in this story? Think of all those medieval works we have already read, and the medieval ideology we have studied.
Write 300 words on what you have found.