Large and Small: Understanding Map Scale
Students of geography typically know how to use a map’s bar scale to estimate the distance from one location to another. They can also use the representative fraction (RF, 1:24,000, for example) to do similar tasks. But ask them if they need a large or small scale map to explore the trails in the town park or the route a car might take from New York to California and they are stumped. In short, they can use map scale, but don’t really understand map scale.
My intervention is designed to teach about map scale for understanding, which should also help in its use and connect it to real world use. In particular I want students to understand:
- Larger scale means more potential details can be seen, smaller scale means fewer details.
- Larger scale maps cover smaller areas (details of one tree, rather than a forest), smaller scales cover larger areas (rivers in a country, rather than paths trough a town park).
- Using a map to find an answer depends on it being at the appropriate scale.
- The RF is like a fraction, a larger fraction (a bigger piece of pie) means a larger scale.
The intervention takes advantage of active learning tapping both a simulation component and a constructionist component.
The first element is an enhanced online world map, akin to Google Maps. The difference is the addition of a few tools. Students can enter a scale by keying in a number in an input box. In short, they’d put in in x in 1:x. The map responds by “zooming to” that scale. There’d also be two buttons labeled “larger scale” and “smaller scale.” Each one would change the scale by a factor of perhaps 10. Thus, hitting the larger scale button would change the scale from 1:1000 to 1:100. I’d also like my map to cover scales beyond 1:1, that is 2:1, 10:1, etc. I’d also like a way to visualize that 1:1000 is smaller than 1:100 visually, perhaps by using a grid of dots and turning one of the 100 or one of 1000 bright red.
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| Mock Up of Interface of First Element |
The workflow might include a series of problems asking, essentially, what scale map might be appropriate for a map showing:
- your walking or driving route to school
- where you hid a treasure in your back yard
- a car trip out of state (or country)
- which states in the United States grow wheat
- countries that are members of the European Union
The second element of the intervention involves students drawing their own maps. They’d do so on the left pane of a window. That would be the “real world” side. They might sketch a penny, a pencil, a toy bicycle. The other pane would, in as real time as possible, show the representation of the object at whatever scale is assigned in an input box as noted above. As before the student would also have access to a “larger scale” and “smaller scale” button to adjust the mapped representation.