1. More DFDs
Class 12

2. More examples Order Processing System Registration system
Grocery store system

3. Let’s try another example
We know customers send orders to the organization and the organization sends out the products ordered with a bill for those products.
Within the organization there is an order processing system.
The Order Processing processing system accepts and records data about orders and then send a message to customers. The system accepts orders only if sufficient inventory exists. Inventory files are updated to indicate the inventory depleted. An Orders file is updated to record the new order. After the order is recorded, the customer is sent a confirmation note.

4. Registration system
Draw a context level and zero-level diagram for a class registration system. Students will request courses and receive a class schedule. Departments will provide a list of courses.

5. Grocery store system
A grocery store has just implemented a new sales system. When a customer has selected the items for checkout, the item is scanned. The system is able to identify the item purchased because of its bar code. The system then looks up the price of the item from a prices file. Once all items have been identified, a total price is computed and given to the customer.