"An escalator is a moving staircase with steps that go up or down. This book discusses how an escalator is based off a conveyor system, moving objects up and down using gears. This form of transportation has made it more convenient to go from one floor to another without walking up flights of stairs. So, next time you have a chance to ride an escalator, hold on to the handrails and get a free moving staircase ride! This book will allow students...