Guy,

You cutting it fine; five or by this time four more days to go.

Spend a little time with http://www.ferg.org/papers/jackson--a_system_development_method.pdf and also ERD's Founders (Codd, Date and Chen) and find out WHY they came up with ERD (reasons 1st, 2nd and 3rd normal forms;etc) and a standard(structured query language; and also why JSDM.

WHEN is also a good consideration; what happened in IT in the 1970 and early 1980s; because this is the time these "tools/methods" were proposed and developed. WHAT problem were they trying to solve: for example, ERD and SQL solved a problem of non-standardised data and access methods. Most databases at the time consisted of flat files, network and hierarchical data bases; each with proprietary access methods. 

At the time, Edsger Dijkstra wrote a seminal paper on the "goto-less program" (not verbatim); which in some way began to introduce the notion of "structure" rather than spaghetti code caused by using Gotos. JSDM tried to solve some these "structured" problems as well.

After you’ve demonstrated that you have a reasonable understanding of ERD and JSDM, show HOW you’d implement and Order System using ERD and JSDM. Use a draw tool and create an ERD with CUSTOMER (1:M) ORDER (1:M) ORDERLINE (M:1) PRODUCT. Eg http://www.tonymarston.net/php-mysql/database-design.html#figure7 (provide reference)

Then using the ‘Entities and Actions’ arguments in the Jackson document above, draw an action diagram for ORDER, and its relationship with CUSTOMER and PRODUCT. Argue that the CUSTOMER must first exist before an ORDER is placed!

All the best,

K