If many pebbles are placed inside an empty cup, the amount of space they occupy is called volume.The volume is the total space the pebbles take up inside the cup, even though there are small air gaps between them.To measure the volume of pebbles, you can use water displacement:Fill a measuring cup with water and record the volume.Add the pebbles into the water.Record the new water level.Subtract the original water level from the new level. The result is the volume of the pebbles in milliliters (mL) or cubic centimeters (cm³).