Harry hadn’t bothered to say anything and had instead demonstrated by transfiguring the books nearest to him into a flock of furious crows and pointing them in Smith’s direction. Smith, and the rest of the group, had yelped, and immediately ducked to cover their heads. Harry very kindly transfigured them back before they could do anyone any harm (though Dennis Creevey did let out a yelp when a book landed on his head).