It started as one small lie. You said you'd finished your reading homework when you hadn't. Easy. But then your teacher asked what the book was about, so you made something up. Then your friend wanted to borrow it, so you said you'd left it at home. Now your mum mentions it to your teacher at parents' evening — and your teacher looks puzzled. Each lie needed another lie to hold it up. You can feel the whole thing getting wobbly. One true sentence at the start would have ended it. Now you're not even sure you remember every version you've told.