This post was written by Peter DeCraene, a 2021-22 Albert Einstein Distinguished Educator Fellow at the Library of Congress.
Parts of my family live all over the United States, so calling them (yes, we still do that sometimes) requires checking the time zone in which they live. With the twice-yearly switch between standard and daylight savings times, and the accompanying discussions about eliminating one or the other, I often think about how we track time. So I was excited to come across this item.
Ask students to observe, reflect, and ask questions about the image. I was first attracted to this diagram by its symmetry and color, almost like a mandala. Art students may notice this as well, and wonder about the color choices and design. History and geography students might notice the various cities listed with different times and distances. Reading an analog clock with Roman numerals might require its own discussion as part of a math lesson.
As students reflect on the image and conjecture about its purpose and design, prompt them to notice the arrangement of the cities listed. Are they arranged geographically, alphabetically, or chronologically? Why might these particular cities have been included? Was there something important about these locations in the middle of the 19th century? Encourage geometry and art students to consider the purpose of the diagram and the arrangement of the clocks: Does the design meet the purpose?
Aspects of this diagram can lead to some interesting lessons across the curriculum:
- What does the phrase “Air line distances” under the diagram mean? The item record has a publication date of 1862, five years before the older Wright brother was born. Discussing how the distances might have been calculated could be part of a STEM and geography lesson.
- This diagram was made before standard time zones were adopted. Social studies students might be interested in who decided the time in each city and why and how time zones were standardized.
- The data on the clocks is an opportunity for algebra students to think about correlation. What would a graph of time versus distance from Washington look like? Different choices about what to put on each axis – distance, time (in minutes or hours), longitude – would lead to different representations.
- There are nineteen clocks on the inner circles, and 38 on each of the outer circles. How might the draftsperson have divided a circle into 19 equal parts? Geometry students learn that some circle divisions are possible using only a compass and straightedge; is a 19-part circle possible this way? If not, what other methods might be used to divide the circle?
This diagram has something to explore for art, history, geography, algebra, and geometry students. Perhaps it might provide a starting point for a cross-curricular collaboration with plenty of time for observing, reflecting, and questioning!
Do you enjoy these posts? Subscribe! You’ll receive free teaching ideas and primary sources from the Library of Congress.