Teacher’s Number Line

From the time of Descartes (1596–1650), mathematicians have described positive and negative integers as evenly spaced points on a line, now called the number line, that extends infinitely in both directions. This usage had made it into some school textbooks by the early 20th century. Particularly at the time of the development of the New Math in the 1950s and 1960s, number lines became part of the school classroom. This example of a number line was developed by Loraine McMillan and sold by Houghton Mifflin Company to accompany the 1972 edition of the textbook Modern School Mathematics. McMillan also prepared the leaflet describing how the number line should be used, as well as a that sold separately.

The teacher's number line consists of eleven cards. Ten of these can be placed end to end to show a number line with the integers from 0 to 100 written in red. The eleventh card is divided into segments but has no numbers marked on it. Each card, unfolded, measures 89 cm. w. x 11 cm. d. The cards were coated with clear plastic so that teachers could mark them with crayons or felt tip markers. The teacher’s guide is printed on blue paper. A mark on it reads: Teacher’s number line; teacher’s guide(/) by (/) Loraine McMillan. Another mark on it reads: houghton (/) mifflin (/) company. A third mark reads: 1972 .

This example appears unused. It was received in 2012, and had been the property of Harvard University mathematician Andrew Gleason.

References:

P. A. Kidwell, A. Ackerberg-Hastings, and D. L. Roberts, Tools of American Mathematics Teaching, Baltimore: Johns Hopkins University Press (2008), pp. 202-203.

Max Beberman and Bruce Meserve, “The Concept of a Literal Number Symbol,” Mathematics Teacher; 48, 1955, pp. 198–202.

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