Saturday, June 5, 2010

Topographic Maps

How do you teach kids (or adults) how to read a topographic map? What do all of those contour lines mean anyway? This three-dimensional, hands on project is a great way to learn how topo maps work.

Papa and the boys are getting ready for a back packing trip next month. They have been learning a lot of things in preparation for the trip. For example, they have calculated how heavy their back packs can be at no more than 20% of their body weight. Another important skill to know is how to read a topo map.

Papa is a long time hiker, back packer, rock climber, mountaineer etc. So he knows all about top maps. You can find lots of general information on-line such as What is a Topographic Map? and Topographic map so you can read all about it, and even look at pictures, but nothing is as good as a hands-on-get-dirty-3D-learning-project!

A topo map of where we live:

Here is what you need:
  • plastic tub
  • dirt/clay/mud
  • piece of plexi-glass, clear plastic, as large as the tub
  • water and something to color it (a little powdered milk works well)
  • markers (if you use wet or dry erase you can easily clean off the plastic when you are through)
  • ruler

Day 1:

Build a land form model in your tub using dirt, mud, clay, etc. Make sure you have hills, valleys, mountain peaks, canyons, ridges and any other land forms you can think of or want to include. Let it dry and get firm for about 24 hours or so.

This is what our completed 3D model looked like:

Day 2:

Mix some powdered milk into the water. You just need enough so that it is not clear. You want to be able to see the edge of the liquid against the dirt.

Place the ruler in the tub with zero at the lowest point (sea level). Choose what interval you will mark at. We chose to fill the tub at 1cm intervals.

Next, pour the liquid until it reaches your first mark (i.e. one inch, 1cm)

Now lay the plastic over the tub and look straight down at it from the top. Trace the outline of the water at the first interval. You will gradually add contour lines for all of the different elevations.

Continue for the remaining intervals. Every 5th interval can be in a different color and show the "elevation" for an index line. When all of the land forms have been submerged you have a completed topographic map of your land form.

Now everyone has a much better idea of what all of those contour lines are on the topo maps!