Structures

All structures give support or create a shape. You can find structures everywhere. Bridges, buildings, chairs, shoes, plants, spiderwebs, tables, and even your own body are all structures. A structure’s shape, size, and what it’s made of depend on what the structure does and how strong it needs to be.

When structures give support, they either experience a pull (tension) or a push (compression). Structures in tension, such as ropes, cables, or blimps are made from stuff that is good at pulling. The materials in tension are usually thin. Structures under compression, such as elephant legs and courthouse columns, are made from hard stiff stuff. Compared to structures under tension, structures under compression are much thicker. When it comes to structures, form (the size and shape) depends on function (what it does).

Build support for Bill by watching the “Structures” episode.

The Big Ideas

• The shape of a structure depends on what it does.
• The strength of a structure depends on its shape and what it's made of.

Did You Know That?

• Modern skyscrapers are designed to sway in the wind and in earthquakes?
• The longest bridge in the world in the Humber Estuary Bridge in England – it’s 1,410 meters (4,626 feet) long?
• All three of the floating bridges in the United States are located in Washington state?

Books of Science!

• “Unbuilding” by David Macaulay. Published by Houghton Mifflin Company, 1980.