Although protractors began to appear in practical geometry textbooks in the 18th century, it was not until the turn of the 20th century that they were used systematically in mathematics teaching in American schools. Some protractors were small and inexpensive, intended for purchase and use by individual students. These might be made from new materials, such as plastic. Other protractors for educational use were oversized, designed for teachers to provide demonstrations of concepts at the blackboard. Two protractors in the collection were manufactured in Japan and displayed at the 1876 World's Fair to help demonstrate the modernization of education in that nation.
"Protractors - School " showing 1 items.
- In the 16th and 17th centuries, surveyors and navigators began to use instruments made especially for measuring off angles. These were generally small instruments made of metal and finely divided. In the years following the Civil War, as the number of American high schools grew, so did the number of students studying practical geometry and trigonometry. To teach them, teachers used inexpensive protractors made for use at the blackboard.
- This example is made of fiberboard, painted white on the front, and has a wooden handle so that it can be held upright. It is divided along the edge to intervals of 5 degrees. By comparison, most protractors are divided much more finely. The Eugene Dietzgen Co. of Chicago sold blackboard protractors like this one from about 1925. This example dates from around 1950 and was used at Montgomery College in Takoma Park, Maryland.
- Currently not on view
- date made
- ca 1950
- Eugene Dietzgen Company
- ID Number
- catalog number
- accession number
- Data Source
- National Museum of American History, Kenneth E. Behring Center