$1.$ Working in a team consider a simple microwave oven commonly seen in a kitchen today. Write a detailed narrative of how the device is used $.2.$ Identify what you think are the principal use cases for the microwave, by extracting them from the narrative looking at the verbs and noun$-$verbs combinations in that description. $3.$ Brainstorm over your narrative to identify the nouns and verbs and adjectives to create: a$.$ A list of classes that you think are important and play a role in the device, b$.$ The objects that 'work' or collaborate together or use other objects to do their work. c$.$ Write the objects, and their responsibilities on a set of cards as shown the example below d$.$ Then write down on the same cards the other classes on the right that they original objects collaborate with $($work with$)$ to get those responsibilities fulfilled. At the end of this exercise you should have a series of cards filled in and a narrative description.