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Cobblestone American History and Current Events for Kids and ChildrenCobblestone American History and Current Events for Kids and Children

Cobblestone American History and Current Events for Kids and Children January 2019

COBBLESTONE is the award-winning and respected leader in the study of American history for young people. COBBLESTONE tells America’s story through a unique mix of captivating articles, lively graphics, historical photographs, primary sources, and maps. Each themed-issue examines historical events in detail making them exciting and relevant to today. A must-have for every history classroom and media center. Grades 5-9.

Country:
United States
Language:
English
Publisher:
Cricket Media, Inc.
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9 Issues

IN THIS ISSUE

access_time3 min.
getting started

Imagine that you lived centuries ago. We’re talking before the invention of trains, cars, or airplanes. You get where you need to go by walking. And the shortest way to get from where you live to a nearby village involves crossing a river. Usually, you ford the river. But heavy rains can make that route dangerous. When that happens, you have to walk around the river. That is a much longer trip. One day, you discover that a massive tree has fallen over the river where you normally cross. You recognize right away what the tree offers. It is a way to reach the other side of the river quickly and with dry feet! The first bridge most likely was “discovered” in this way. And what a discovery it was! People…

access_time4 min.
bridge basics

Bridge Key Tension Compression Here’s a look at six basic bridge types. For help with bridge terms, check out pages 8–9. BEAM Beam A beam bridge was one of the earliest bridges. It is also one of the simplest and least expensive to build. Its main elements are a straight horizontal beam supported by a pier at each end. The load pushes straight down on the beam. It is great for short distances—usually not more than 250 feet. Modern beam bridges made of multiple girders supported by piers can be much longer. Beam bridges frequently are used to carry one road over another road. The longest modern beam bridge over water in the United States is Lake Pontchartrain Causeway in Louisiana. It is two parallel bridges, the longer of which is 23.83 miles. The longest…

access_time2 min.
a balancing act

Anchorage The place at which the main cables and other supporting elements are secured to the ground Abutment The structure that supports the point at which the bridge connects with land Substructure The lower support elements Caisson The structure that becomes an underwater foundation Beam/Girder The load-bearing horizontal structures that extend a bridge’s length and support the deck Main Span The distance between the two main towers or piers Tower/Pylon A tall steel structure that supports high-tension wires Deck/Roadway The area or path over which people and vehicles travel Foundation The base through which the load is transferred to the ground Superstructure The elements that absorb the live load Side Span The distance between the initial access to the bridge and the first tower or pylon Pier The vertical structure that rests on the ground and that supports connecting beams or girders Main Cable The cable that drapes over the towers and from which the…

access_time6 min.
under construction

How does a bridge get built? It’s a massive job that takes a lot of planning. Many questions are considered before any building starts. What kind of bridge is needed? How long does the bridge have to be? Will the bridge cross over water or land? What will use it? Cars? Trains? People? How much traffic will it carry? Will that change in the future? What weather issues will impact it? How much money will it cost? Who Pays? Whether building a new bridge or repairing an old bridge, it costs a lot of money. State and local governments are responsible for the roadways and bridges within their boundaries. To help pay for major construction projects, most local governments collect gas and vehicle taxes or fees from their residents. Highway tolls are…

access_time2 min.
just build it

Here are some hands-on activities to understand the ways a few basic bridges work. PUSH AND PULL You Need 4 craft sticks 2 hardcover books that are the same thickness glue stick or bottle of glue 1. Put the 2 books cover side down about 4 inches apart on a flat surface. Rest the craft stick across the gap between the books so that about a half inch of each tip rests on the books. 2. Gently press down on the center of the stick with your index finger. Your finger is applying force that compresses the top of the stick and puts the bottom of the stick in tension, like live load on a bridge’s deck. 3. Glue 3 craft sticks together so that 1 vertical stick is glued between 2 horizontal sticks. Once it is…

access_time5 min.
chicaco on the move

Humans have engineered all kinds of bridges. Some of the most interesting are moveable bridges, or drawbridges. Moveable bridges are designed to allow their main spans or decks to be temporarily moved out of the way to allow water traffic to pass below. For a city such as Chicago, moveable bridges solved a lot of problems. The city is divided into three by the Y-shaped Chicago River. It also is located at the southwest tip of Lake Michigan. Moveable bridges allowed the city to grow while providing ways for people to easily get around. Chicago began as a swampy French and Native American trading outpost on the flat Midwest prairie. By 1837, it was incorporated as a city. It grew rapidly, thanks to its location on Lake Michigan and the Chicago River.…

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