Download or read book The Fort on Fourth Street written by Lois Spangler and published by Arbordale Publishing. This book was released on 2013-01-01 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt: Building a fort in the backyard, a grandfather and granddaughter get help from six simple machines: lever, pulley, inclined plane, wheel and axle, screw, and wedge.