9 replies to this topic

[Dennis McClendon]

I'll be talking with elementary schoolteachers in early February about how to teach the concepts of mapping. I'll be fleshing out an outline in the next few days, and will share it here, but generally I'll focus on the idea that mapmaking is "intelligent tracing" that is selective about what features are included, symbolizes rather than merely picturing, and includes information (such as feature names) not visible on the landscape. I try very hard to analogize mapmaking to the kind of selectivity and editing that's found in writing, that makes a brief report on a topic different from a book, a summary of headlines different from an entire newspaper.

When I speak in classrooms, I generally encourage them to make maps of the classroom itself, or of the schoolgrounds, or maybe the block surrounding the school. I do little demos using tracing paper and colored pens, drawing first all the water, then the roads, then the building symbols, and finally the labels. To keep the emphasis on editing and selection, I don't encourage them to draw fantasy maps.

For older kids, I sometimes will show a modern map of the Iberian Peninsula and one from the 19th century, pointing out how little change there is from modern satellite imagery. Once I've asked how the old guys did that without being able to see the earth from the sky, I'll sometimes talk about very simple principles of finding latitude (from sun or star elevation) and longitude (from time difference with Greenwich).

I'd be interested in thoughts about what other concepts I should suggest to these teachers, or exercises they might find useful. I've been pondering all weekend some kind of simple exercise to show the theory behind GPS, because too many people (probably including these teachers) think the satnav displays in their cars are beamed from satellites like television programming. But I don't know that something showing only triangulation (without precise timing differences) adequately explains the concepts behind GPS.

[Hans van der Maarel]

I'd be interested in thoughts about what other concepts I should suggest to these teachers, or exercises they might find useful. I've been pondering all weekend some kind of simple exercise to show the theory behind GPS, because too many people (probably including these teachers) think the satnav displays in their cars are beamed from satellites like television programming. But I don't know that something showing only triangulation (without precise timing differences) adequately explains the concepts behind GPS.

My college surveying teacher explained it by having us imagine the classroom as (part of) the universe, the 4 corners as satellites, an arbitrary location as the GPS receiver and pieces of string to represent the measured distances. But I don't think that would work as well with highschool kids.

Actually... maybe it could.

Take 4 kids and a tape measure. Position 3 kids on "known points" (i.e. the satellites) and 1 kid somewhere in the middle. Have him/her measure the distance to 1 other kid. Then explain that that is not enough to fix a position. Measure the distance to a second kid. Still not enough. Measure to the 3rd kid and you've got it pinpointed (bar measuring errors).

Of course this is 2D geometry, rather than 3D, but at least it will give them a basic understanding of the principles and you a base to start from.

And tell them that all a GPS satellite does is pretty much limited to shouting the time

-- edit --
And not to forget: congratulations on getting the chance to do this. I've been thinking of simply contacting the local schools and offering a guest lesson... maybe I should give it a go.

[BioGeoMan]

I had a geography professor, who on the first day of our course, had us hand draw a mental map of where we live in relation to the university without showing any man-made landscape features (e.g. roads, businesses, signs). Good stuff!!

[Nick Springer]

I've been pondering all weekend some kind of simple exercise to show the theory behind GPS, because too many people (probably including these teachers) think the satnav displays in their cars are beamed from satellites like television programming. But I don't know that something showing only triangulation (without precise timing differences) adequately explains the concepts behind GPS.

During usability testing of our GPS Navigation software, one of the first questions I asked each participant was "How do you think GPS works?" 80% of the responses were "the GPS device in my car sends a signal to the government GPS satellites in space which are tracking my location on the map." It was very enlightening to them, and somewhat of a relief, when I explained how the satellites were passively sending signals that the device in the car uses to triangulate it's position and that no information was passed back. I wonder how many people don't buy GPS unit because they think they will be tracked by the government?

So I think a brief lesson on GPS would be useful as part of your offering.

[Jimbo]

When I first did my course I had to draw a map from my mind of the entire country of Canada, not easy to do but interesting. The lesson of the exercise was not to see if our hands were steady, not needed since it's now digitally based but more a map interpretation exercise. Of course my carto-design teacher only gave a check mark for that, man she could have atleast made the exercise worth 5%.

[natcase]

I'd be interested in thoughts about what other concepts I should suggest to these teachers, or exercises they might find useful.\

Dennis: you basic direction sounds good.

I've tried to do this twice. about 12 years ago, I started an exercise with a small group of 4th-graders, where we were going to make a map of our neighborhood. I go t aerials, and started having them trace. They got bored and really squirrelly really fast (it was late in the school day). The project kind of fell apart.

More recently, I went to my son's preschool, and talked to them about how all the maps of the world are collections of littler maps—someone makes a map of a property, and then someone collects maps of a while lot of properties until you have a map of a town, then some collects maps of towns and you get a map of a state, etc. Oversimplified sure, but it related itself to the simple exercise we made of mapping a little part of the classroom on graph paper, and laying masking tape on the carpet around a classmate who was lying down.

To me, differentiating maps from pictures is too subtle a point for elementary school. Students want to label pictures, so that is a moot point. It seems to me like mapping to an elementary school student is going to be measured drawing, with classed and complete picture layers and labels. Projection maybe as a very rough concept (I'd hold off on details of projection until Geometry in high school).

I like the GPS/measuring tape ideas.

So, to your original question, basic concepts might be:

- Scale: make a 1:1 outline map of a classmate on a BIG piec of graph paper, then look at what a 1:10 map would be, 1:100...

- Layers: Have the students take a big picture of something familiar (simple aerial of the school grounds? complex picture book illustration like Richard Scarry?) and take separate pieces of tracing paper over it and draw a few thematic layers from the original image.

- Symbol classes: have the teacher make a map of the classroom with one space for each student, along with colored slips in say 5 different colors. Divide the class up into groups, and have them each come up with a multiple choice question to ask each student about something non-invasive (food preference, favorite sport, birthday season, how many siblings). The teacher then has each group tell what its question was, and then has the whole class fill out its answers on one of the paper colors. Everyone does this for each question, then the groups reassemble and make a theme map, having to decide on a symbolization. Teacher looks at maps and talks about quantitative vs qualitative theme maps.

- Projection: Give the group a slightly deflated basketball or beach ball. have them draw on it in a non-fast-dryig ink. Roll it out on a piece of paper.

Keeping interest is everything. Once you get abstract and the little buggers lose interest, you're hosed.

[frax]

in a little while I while have some visitors from a school to my office - where a friend's wife is teaching - she will bring two 10-year old students and we will look at maps and stuff. I am not 100% sure about what to tell, I need to think about that more - but this is some input in this thread!

Most of the work I do is a bit too complex for a 10-year old I think, though, like climate change - so I think I will stick to more basic stuff.

[Dennis McClendon]

If it helps anyone, here is the general outline from which I spoke to the teachers:

M A P P I N G•••P R I N C I P L E S
Mapping is just “intelligent tracing.”

• Details are left out; labels and invisible data are added in

Mapping uses symbols

• Some are representational; some are theoretical
• Examples: blue water; red highways; brown elevation lines

Level of detail depends on scale

• Large scale maps can include greater detail
• Features sometimes exaggerated, combined, simplified, or displaced

Large-scale maps generally have a uniform scale
Reference maps include information “objectively”
Thematic maps select and highlight information to make a point
Foreground information vs. background information
Latitude—how far north or south of the equator?

• easily determined from sun or star angle

Longitude—how far east or west of some agreed-on line (like the Prime Meridian)

• starting point is a political issue, not a natural one
• time difference the easiest way to determine longitude

GPS: nothing more than satellites announcing the time

• your GPS unit figures out where it is using triangulation
• shows maps it already has in memory

A C T I V I T I E S
Maps in videogames like Diddy Kong Racing

• planimetric view shows entire track

Maps for wayfinding: CTA map or Chicago bicycle map
Map the classroom, using floor tiles to scale the space
Map the school vicinity, tracing over an aerial photo

• figuring out what’s important
• labeling things that aren’t visible

O N L I N E ••• R E S O U R C E S :
maps.google.com Google street maps, aerial photos
maps.live.com Microsoft Virtual Earth street maps, aerial photos, and birds-eye view photos
mapper.acme.com Google maps, aerial photos, and USGS topographic maps
maps.cityofchicago.org/kiosk/ Chicago building outline maps
english.freemap.jp Free, downloadable outline maps in PDF format

notes prepared Feb 2007 by Dennis McClendon dennis@chicagocarto.com

[hphillips]

Dennis -
Thanks for sharing the outline of your talk to schoolteachers about mapping. Having heard the humor and clarity of your presentations at NACIS meetings, I am sure the talk was both enjoyed and appreciated by the teachers who attended.

I do have one niggling point with regard to terminology of GPS operation and I apologize that I did not see this thread before your talk to mention it. There seems to be a fairly common misuse of the word 'triangulation' for the method by which GPS determines position, when the method is more accurately described as trilateration. There are no angles measured by GPS receivers; instead distances are calculated based on signal transit times. Hans' exercise with the four students and the tape measure involves no measured angles, only measured distances and hence is a good simple model for the method of position determination by GPS.

...
GPS: nothing more than satellites announcing the time

[*]your GPS unit figures out where it is using triangulation

[Dennis McClendon]

Thanks. I didn't think about the word triangulation having such a precise technical meaning.