Simplify the following text for a Grade 9 native English-speaking person.
Original: A valve is a device that regulates the flow of a fluid ( gases , liquids , fluidized solids , or slurries ) by opening , closing , or partially obstructing various passageways .
Simplified: A valve is a device that helps with the flow of materials ( like gases , fluidized solids , slurries , or liquids ) .