http://en.wikipedia.org/wiki/Timeline_of_historic_inventions#20th_century

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You will type 2 or more paragraphs about the invention you selected.

In the first paragraph you will present an overview of what the invention is and what it does.

In the second paragraph you will share how it has impacted society.

After researching and composing your report the class will be divided into groups of 5 where you will present to each other your opinions and discoveries.  One of the five will be selected as "a Great Invention"

In the next round of discussion the 5 Great Inventions will make a verble presentation to the whole class who will then vote to determine which is the "Greatest Invention of the 20th" Century.