So there she sat, with her knees up to her chin, her eyes fixed on Paul (I think that's why I was there; he gets very embarrassed by some of the girls!), as he very carefully talked her through the need to 'introduce' the dissertation topic in a logical way to the reader.
"What do you mean by 'introduce'?" said Sarah.
"Well," said Patient Paul, "Let's think what happens when you go out for an evening."
"I get drunk!"
"No, Sarah, before that. Let's assume you see a boy looking at you..........."
"I stick my tongue out!"
"Stop! You are sober, you see a boy looking at you, he looks nice, he smiles at you......"
"I go to the loo!"
"No Sarah, you've just come back from the loo! He smiles at you and your eyes meet. Then he walks towards you. What do you do?"
"Go somewhere else!"
"Look: you can't. He walks towards you, and stops right in front of you. He's nice, and he says something like 'Hi. My name is Lee," and holds out his hand. Now what do you do?"
Sarah thought for a bit. "I suppose I would shake his hand."
"So, would you tell him your name?"
"I might say I was someone else!"
"Well ok - you tell him you are someone! And that is very much like the start of the dissertation. There's a short bit at the start where you introduce yourself to the reader, just enough to get their interest. But now you have to introduce the topic, to make them want to read further. So, going back to the boy you've just met and to develop the relationship, what might you ask him?"
I saw Sarah process this for a moment. Then she said "I'd ask him: 'are you gay?'"
I managed not to burst out laughing, but I saw Patient Paul put his head in his hands!