Secrets of Lost Empires II—China Bridge & Roman Bath

Student Handout

Tasty Arch

Chinese leaders have chosen you to build an arch bridge. First, you must get ready for this great feat. Before building the arch, you must prepare the stone blocks. Cut the cookies crosswise with a plastic knife. If you look closely at an arch, you'll see that the blocks are not rectangular, but trapezoidal solids. The face of the block on the inside curve of the arch is narrower than the face on the outside.

To create this stone-block shape on your cookie pieces, do the following:

• Lay a cookie flat on the sandpaper.

• Place your 3 middle fingertips on the long edge of a cookie.

• Holding a thumb on one short edge and your pinky finger on the other, gently and smoothly swipe the cookie back and forth two times. The combination of pressing off center and sanding four times will bevel your cookie blocks the correct amount for a small arch.

Now assemble your arch on its side. Line up the inside edges of the blocks as evenly as possible; don't worry about the outside edges. Lightly grasp all of the blocks and tip the arch into a standing position placing it on your sandpaper. Before you let go, have your teammate carefully fix any blocks that may have moved out of place. It may take a few tries before you succeed, but when you do, you'll have a genuine Roman arch supported only by its own weight.