tread

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References

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The Colosseum, Rome, Italy. Giant amphitheatre built in Rome under the Flavian emperors. (ancient architecture; architectural ruins)

New Seven Wonders of the World

Close up of periodic table, focus on nickel, copper, zinc, palladium, silver, cadmium

When Was the Periodic Table Invented?

World map. Continents. Oceans. Mendel thumb ok

Just How Many Oceans Are There?

Franklin D. Roosevelt, who formulated the Four Freedoms.

7 Alphabet Soup Agencies that Stuck Around

Adolf Hitler (Nazi, nazism, German leader).

9 Things You Might Not Know About Adolf Hitler

Bar graph of the United States Death Toll during major events. Infogram chart.

U.S. Death Toll During Major Events

solar eclipse, sun, moon, astronomy, space

How Do You Tell the Difference Between Total, Annular, Solar, and Lunar Eclipses?

tread

staircase

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In staircase
…a step is called its tread and the vertical front its riser; steps are placed between strings that are inclined to the angle of the staircase; strings are supported by newel posts that also support the handrail, forming a balustrade.
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