An ion is an atom that has either a net positive or negative charge. Balloons, when rubbed against surfaces, can build up a negative charge. When placed in front of a positively charged object, the two will attract. We are going to use this to separate salt and pepper.
Mix salt and pepper together on a plate. Take a balloon, fill with air and rub against your head. Hold the balloon over the salt and pepper mixture and see what happens. Design a presentation both showing your experiment and why it happened. Not all experiments always work, if your experiment fails, postulate as to what might have caused the issue.