Levitate a magnet
Popular for its simple yet mesmerising effects, kids just love levitation experiments.
In theory all you need to conduct your own levitation is two of the same magnets, but orientated so the poles are repelling each other. However the magnets will flip themselves over if they are not physically restricted from doing so. The specifics on what to use would depend on the size, thickness and strength you require. We suggest taking a look at some of the many youtube videos of this experiment for guidance.