Use of a mannequin’s head and a newly-purchased couch to refute the defendant’s version of the events on the day she shot her husband was properly allowed as a demonstration. Because the evidence did not constitute an experiment, the State did not have to show that the circumstances were substantially similar to those at the time of the actual shooting. As a demonstration, the evidence was admissible because it was relevant (it was probative of premeditation) and not unfairly prejudicial.