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.