boil water put tea in a pot when the water is boiled pour it into the pot wait 5 mins pour the tea into cups add milk drink

where is the water coming from

where is the kettle

how do you get the water into the kettle

how do you know how much water to put into the kettle

what if there is no water/kettle/electricity?

what if your fill sensor fails?

what if your boiling sensor fails

where's the pot, what if there isn't one? should we have thought of that before boiling the water?

where is the tea, which kind of tea? should we have asked first, perhaps we shouldn't have started this if we don't have the right tea?

similar questions about filling and sensors

are you sure it's boiling? how can you make sure that the machine doing the pouring got the right 'done' signal from the kettle?

How do you make sure that the machine pourer knows where the pot is?

What if the pot tips over during pouring?

etc.

Ask them to describe the steps needed to make a cup of tea, they will say something like:Now the fun begins. You need to start asking these kinds of questions:Boiling water?Put tea in pot?Pouring boiling water?And so on - you can go on for hours. They will get bored and say "yes but this level of detail is silly", you can sagely smile and say "exactly".ps. after all that tell them the customer actually wanted coffee to go with an extra shot and not a Japanese tea ceremony - surely you should have known that, wasn't it obvious from the requirements?