Robert and Deborah Bain wrote:

> The theme of the convention
> is "bridges" so we would like to keep the interactives as closely
> related to that as possible.

Deborah,

You may also want to take a look at the Nova "Super Bridges" site. Users
have to select the appropriate bridge design for different kinds of
spans.  It also has a teacher's resource page with some simple
activities that explain the physics of bridges.

http://www.pbs.prg/wgbh/nova/bridge

Richard Urban, Assistant Curator
Historical Society of Delaware
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