In 5th grade we created this Fan Model below that was used to demonstrate how the molecules actually moved in the chromatography test based on their different properties.  There were several different items- packing peanuts, rocks, styrofoam balls and hook and fastener strips that represented the different molecules on the chromatography strip and when we turned on the fan these items moved in different ways depending on their properties.  This model helped students to understand the key concept that different molecules have different properties and therefore act differently.