Jolina says, ‘Beautifully put,’ and her smile gives me the confidence to carry on.

‘It’s amazing,’ I say, nodding at the miraculous dot, ‘because that is basically what every single thing in the universe is made of.’

Someone leans close to me. I smell lemon and vanilla. ‘Calm down, Mega Knickers,’ Bella whispers in my ear.

An icy feeling sweeps through me and all my excitement vanishes. Ed tuts, which only makes Bella laugh and say, ‘What?’

Jolina’s started to talk about lasers, but I can’t concentrate on what she’s saying, and it’s not just because Bella made me feel stupid. Knowing that Ed has told Bella all about the workshop, and that they must have been laughing about me behind my back, makes me feel as alone as that buzzing atom on the screen.

I fall to the back of the group, and watch the rest of the tour in silence. At the end, when Jolina says, ‘Does anyone know how many quantum numbers are needed to describe the properties of an electron in an atom?’ I look away.

‘Two?’ says Ed.

Four, I think. It’s four.

‘No,’ says Jolina. ‘There are four.’

THIRTY-TWO

When the tour is over, we’re taken to a lab where we start defusing alien bombs and illuminating streams of water drops with a strobe. The teacher tells me I’m ‘a natural’ and even hands me a prospectus for the university. I hold the brochure on my lap as Ms Edgecombe dismisses everyone for lunch. ‘Make sure you’re back here in an hour,’ she says.

Once everyone else has gone, I go out into the corridor. I find Ed leaning on the wall opposite, waiting for me. He stands up. ‘Ready to work on our presentations?’ he asks.

I look at him. I’d forgotten all about that. Right now, Ed doesn’t look like someone who would ever allow a balloon to be stuck to his hair. He just looks like the tall, good-looking boy who for years has either ignored me or tried to beat me, depending on what’s suited him best.

I shrug. ‘OK.’

‘So where shall we go?’

‘Wherever.’ I know I sound rude, but I don’t care. ‘Here?’ I say.

‘Here? In this corridor?’ He laughs. ‘Let’s go to that cafe we walked past.’

‘Fine,’ I say, and I follow him outside, across the lawn and up a flight of stairs.

We stand outside the crowded cafe and students pass us, looking curiously at our uniforms. ‘Do you think this is OK?’ he says, hanging back.

I look at the prices on the menu. ‘It’s fine,’ I say, pushing open the door. ‘Come on.’

After Ed’s bought sandwiches and crisps, and I’ve got a hot chocolate, we find a free table. Even though the cafe’s busy, it’s strangely quiet because so many of the students are working. I get out the roll I brought from home, my phone and a pad of paper. ‘So,’ I say, ‘do you want to go first? Read through your notes?’ I write ‘Ed’s Presentation’ at the top of a piece of paper.