Hicks 
Escalators [PDF ebook] 

An escalator is a moving staircase with steps that go up or down. This book discusses how an escalator if based off a conveyor system, moving objects up and down using gears and chains that are connected to the steps, flattening them out at the top and bottom so people can easily get on. 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 to analyze data to determine if a design solution works as intended to change the speed or direction of an object with a push or a pull.