'Yeah, the DA's good,' said Ginny. 'Only let's make it stand for Dumbledore's Army, because that's the Ministry's worst fear, isn't it?'

There was a good deal of appreciative murmuring and laughter at this.

'All in favour of the DA?' said Hermione bossily, kneeling up on her cushion to count. 'That's a majority — motion passed!'

She pinned the piece of parchment with all of their signatures on it on to the wall and wrote across the top in large letters:

DUMBLEDORE'S ARMY

'Right,' said Harry, when she had sat down again, 'shall we get practising then? I was thinking, the first thing we should do is Expelliarmus, you know, the Disarming Charm. I know it's pretty basic but I've found it really useful — '

'Oh, please, ' said Zacharias Smith, rolling his eyes and folding his arms. 'I don't think Expelliarmus is exactly going to help us against You-Know-Who, do you?'

'I've used it against him,' said Harry quietly. 'It saved my life in June.'

Smith opened his mouth stupidly. The rest of the room was very quiet.

'But if you think it's beneath you, you can leave,' Harry said.

Smith did not move. Nor did anybody else.

'OK,' said Harry, his mouth slightly drier than usual with all these eyes upon him, 'I reckon we should all divide into pairs and practise.'

It felt very odd to be issuing instructions, but not nearly as odd as seeing them followed. Everybody got to their feet at once and divided up. Predictably, Neville was left partnerless.

'You can practise with me,' Harry told him. 'Right — on the count of three, then — one, two, three — '

The room was suddenly full of shouts of Expelliarmus. Wands flew in all directions; missed spells hit books on shelves and sent them flying into the air. Harry was too quick for Neville, whose wand went spinning out of his hand, hit the ceiling in a shower of sparks and landed with a clatter on top of a bookshelf, from which Harry retrieved it with a Summoning Charm. Glancing around, he thought he had been right to suggest they practise the basics first; there was a lot of shoddy spellwork going on; many people were not succeeding in Disarming their opponents at all, but merely causing them to jump backwards a few paces or wince as their feeble spell whooshed over them.

'Expelliarmus! ' said Neville, and Harry, caught unawares, felt his wand fly out of his hand.

'I DID IT!' said Neville gleefully. 'I've never done it before — I DID IT!'

'Good one!' said Harry encouragingly, deciding not to point out that in a real duel Neville's opponent was unlikely to be staring in the opposite direction with his wand held loosely at his side. 'Listen, Neville, can you take it in turns to practise with Ron and Hermione for a couple of minutes so I can walk around and see how the rest are doing?'

Harry moved off into the middle of the room. Something very odd was happening to Zacharias Smith. Every time he opened his mouth to disarm Anthony Goldstein, his own wand would fly out of his hand, yet Anthony did not seem to be making a sound. Harry did not have to look far to solve the mystery: Fred and George were several feet from Smith and taking it in turns to point their wands at his back.

'Sorry Harry,' said George hastily, when Harry caught his eye. 'Couldn't resist.'

Harry walked around the other pairs, trying to correct those who were doing the spell wrong. Ginny was teamed with Michael Corner; she was doing very well, whereas Michael was either very bad or unwilling to jinx her. Ernie Macmillan was flourishing his wand unnecessarily, giving his partner time to get in under his guard; the Creevey brothers were enthusiastic but erratic and mainly responsible for all the books leaping off the shelves around them; Luna Lovegood was similarly patchy, occasionally sending Justin Finch-Fletchleys wand spinning out of his hand, at other times merely causing his hair to stand on end.

'OK, stop!' Harry shouted. 'Stop. STOP! '

I need a whistle, he thought, and immediately spotted one lying on top of the nearest row of books. He caught it up and blew hard. Everyone lowered their wands.

'That wasn't bad,' said Harry, 'but there's definite room for improvement.' Zacharias Smith glared at him. 'Let's try again.'

He moved off around the room again, stopping here and there to make suggestions. Slowly, the general performance improved.

He avoided going near Cho and her friend for a while, but after walking twice around every other pair in the room felt he could not ignore them any longer.

'Oh no,' said Cho rather wildly as he approached. 'Expelliarmious! I mean, Expellimellius! I — oh, sorry, Marietta!'

Her curly-haired friend's sleeve had caught fire; Marietta extinguished it with her own wand and glared at Harry as though it was his fault.

'You made me nervous, I was doing all right before then!' Cho told Harry ruefully.

'That was quite good,' Harry lied, but when she raised her eyebrows he said, 'Well, no, it was lousy, but I know you can do it properly, I was watching from over there.'

She laughed. Her friend Marietta looked at them rather sourly and turned away.

'Don't mind her,' Cho muttered. 'She doesn't really want to be here but I made her come with me. Her parents have forbidden her to do anything that might upset Umbridge. You see — her mum works for the Ministry.'

'What about your parents?' asked Harry.

'Well, they've forbidden me to get on the wrong side of Umbridge, too,' said Cho, drawing herself up proudly. 'But if they think I'm not going to fight You-Know-Who after what happened to Cedric — '

She broke off, looking rather confused, and an awkward silence fell between them; Terry Boot's wand went whizzing past Harry's ear and hit Alicia Spinnet hard on the nose.

'Well, my dad is very supportive of any anti-Ministry action!' said Luna Lovegood proudly from just behind Harry; evidently she had been eavesdropping on his conversation while Justin Finch — 'Fletchley attempted to disentangle himself from the robes that had flown up over his head. 'He's always saying he'd believe anything of Fudge; I mean, the number of goblins Fudge has had assassinated! And of course he uses the Department of Mysteries to develop terrible poisons, which he secretly feeds to anybody who disagrees with him. And then there's his Umgubular Slashkilter — '

'Don't ask,' Harry muttered to Cho as she opened her mouth, looking puzzled. She giggled.

'Hey, Harry,' Hermione called from the other end of the room, 'have you checked the time?'

He looked down at his watch and was shocked to see it was already ten past nine, which meant they needed to get back to their common rooms immediately or risk being caught and punished by Filch for being out of bounds. He blew his whistle; everybody stopped shouting 'Expelliarmus' and the last couple of wands clattered to the floor.

'Well, that was pretty good,' said Harry, 'but we've overrun, we'd better leave it here. Same time, same place next week?'

'Sooner!' said Dean Thomas eagerly and many people nodded in agreement.

Angelina, however, said quickly, 'The Quidditch season's about to start, we need team practices too!'

'Let's say next Wednesday night, then,' said Harry, 'we can decide on additional meetings then. Come on, we'd better get going.'

He pulled out the Marauder's Map again and checked it carefully for signs of teachers on the seventh floor. He let them all leave in threes and fours, watching their tiny dots anxiously to see that they returned safely to their dormitories: the Hufflepuffs to the basement corridor that also led to the kitchens; the Ravenclaws to a tower on the west side of the castle, and the Gryffindors along the corridor to the Fat Lady's portrait.

'That was really, really good, Harry,' said Hermione, when finally it was just her, Harry and Ron who were left.

'Yeah, it was!' said Ron enthusiastically, as they slipped out of the door and watched it melt back into stone behind them. 'Did you see me disarm Hermione, Harry?'

'Only once,' said Hermione, stung. 'I got you loads more than you got me —'

'I did not only get you once, I got you at least three times — '

'Well, if you're counting the one where you tripped over your own feet and knocked the wand out of my hand — '

They argued all the way back to the common room, but Harry was not listening to them. He had one eye on the Marauder's Map, but he was also thinking of Cho saying he made her nervous.