Essays / Development of notation before 1600 AD - advice on how to go about an essay question I have been set [2]

Need advice on how I should go about the following essay question:

"Write an essay detailing the development of notation, starting from a point in time of your choice before 1600 AD. You must include at least 2 references as well as indicate a direction of progression through to modern scoring techniques"

Do I simply need to detail the development/ evolution of notation in this question, or do I need to form a thesis/claim and an argument that I then need to back up with evidence.