I have a party trick for children, which is to make them Apparate (like in Harry Potter) from one end of the room (or garden) to the other. My nieces love this trick - they've almost certainly worked out how it's done, but they keep asking me to do it. It doesn't work with other children watching, though, so it's only good for one (or possibly two) children at a time; and it's easier with a secret assistant. I've searched the internet for similar ideas, but I haven't found any - maybe it is all mine!
Show the child a low stool at one end of the room, and a hoop (or mat) on the floor at the other end. Tell them they are going to stand on the stool, and jump off, which will make them Apparate into the hoop. Get them to practise jumping off the stool on to the floor: this is so that you can see how far forwards they jump, and if you like, get them to say the three D's: Destination, Determination, Deliberation. Then, take them to the middle of the room, and blindfold them, to protect them against splinching (separation of body parts). Tell them that after they have Apparated, they have to keep their blindfold on for a few seconds, for the magic to wear off. Spin them round, and while you do this, your assistant secretly moves the stool to near the hoop. Lead the child to the stool (which is not where they think it is), help them to stand on it, then tell them to jump off; they should land in the hoop. Keep talking to them, while your assistant quickly returns the stool to its original position and leaves the room, then uncover the child's eyes. If you've done it right, the child believes they have Apparated. My nieces really believed it the first time; some other children clocked it straight away, but it's always great to see their expressions when they do it.