Explaining Geocaching

September 2, 2004 12:33 PM

So I am going to take a friend and his 9 year old Geocaching this Sunday. I am seeking a clear and quick explanation on how longitude, latitude, minutes and seconds work - in a way a nine year old would understand. Answers or good links?
posted by BrodieShadeTree to Science & Nature (6 answers total)

Explain simple Cartesian coordinates, how you can locate a point on a plane with the x and y axes. Tell the old-wives-tale about Descartes lying in bed, noticing a fly on the ceiling, and realizing that he could describe the fly's position with just two numbers.

Branch out by showing a plus-shaped graph, with positive and negative numbers on the two axes.

Then get a globe, point out the latitude and longitude lines, and explain that the same system has been applied to the (roughly) spherical Earth. Mention that the Prime Meridian and Equator correspond to the zero point or origin of the earlier graph, and then show some familiar places and how they might be described using coordinates.
posted by Vidiot at 12:41 PM on September 2, 2004

Oh, and explain that you can use decimals or fractions to describe the points between whole numbers on the Cartesian plane. Say that with lat/long, it works slightly differently, and talk about how the unit of measurement there is degrees, which are broken up into minutes and seconds.

And have fun!
posted by Vidiot at 12:44 PM on September 2, 2004

That cartesian product thing seems awfully complex for a nine year old. I think if you just did the globe part, and showed him how the world is divided up with those grid lines - where minutes and seconds are just smaller divisions within the grid lines - it'd be pretty clear. Some mention of how time zones are related to the measurements might also be interesting.
posted by jacquilynne at 1:06 PM on September 2, 2004

You might also want to zero in on your part of the world and explain "see, when we go east, ths number gets higher... when we go north, this number gets lower" and show how it works by using a compass/GPS in tandem [apologies if this is all backwards, I am way too dyslexic to keep track of east and west and lat/long effectively]. Might want to take a look at the confluence points in your area and match a picture of a place, with cooridnates in the latitide/longitude arena, with the map of a place. This page has a good three step explanation that might be a good jumping off point.
posted by jessamyn at 4:16 PM on September 2, 2004

If the kid is nine, it should be familiar with Cartesian coordinates, aka ordinary school graph paper and Battleship. Long/Lat is merely that expanding that to fit the world.

The graphing the kid is familiar with probably takes the form of an A..Z axis and 0..10 axis. The math texts will have exercises where they play connect-the-dot given a series of crosspoints. Little graph-paper ships, ducks, flowers, etc.
posted by five fresh fish at 4:45 PM on September 2, 2004

Any particular reason to teach him lon/lat? UTM is more widely used in the mapping industry, is available on most (all?) geocaching sites, and is easier to use since you don't have to do all that degree/minute/second base-60 arithmetic. Plus it's in meters.
posted by F Mackenzie at 9:21 PM on September 2, 2004