Topography With Potatoes
"Mount Potato"

Concepts:

Topographic lines represent three dimensional contours. Contour lines indicate changes in measured elevation. A steep slope is shown by contour lines close together. When contour lines curve like a "U" or point like a "V," they are pointing toward the uphill or higher elevation.

A & B are steep slopes C (shaped like a "U") is a gentle valley D is a steeper-sided valley collecting stream water

Objectives:	To understand use of contour lines and basic topographic features. To envision 3-dimension from a 2-dimensional map. To understand scale as a necessary mapping element.
Materials:	A real topographic map. Sweet (or white) potatoes, as knobby and deformed as possible. Sharp knife, paper towels or absorbent napkins, shish kabob skewer, paper, pencils, and rulers.
Subjects:	Social Studies & Mathematics

 

Preparation and Procedure: Purchase or obtain potatoes. About 3 days before the classroom exercise, cut potatoes in half. (If potatoes are not nobby enough, or do not have "valleys" or "gullies" in them, carve these into the potatoes.) Push a skewer through each half potato at the highest point. Revolve skewer to enlarge the hole. Then cut each half lengthwise into as many even slices as possible. Handle only one-half potato at a time. Wrap each slice, largest to smallest, in absorbent napkins; wrap the cut and papered half potato in another paper towel. (Drying with paper makes potato slices easier to handle and less subject to mold.)

1. Introduce real topo map to students and explain this is a two-dimensional way of representing the landscape. Ask them what the numbers on the contour lines probably represent, and what value the unnumbered lines represent. Explain to students they will be making topo maps of their potato "mountains." Have students decide the elevation each potato slice will represent.
2. Provide students with sliced half potatoes, paper and pencils. Students can work individually or draw contours of their potato halves on a single large paper.
3. Students unwrap potatoes. Have students insert a pencil into the center hole of the largest potato slice and make a mark on their paper. Now have them draw around the largest slice. (For purposes of this exercise, we'll assume the contour of the largest slice is actually above the level of their paper.)
4. Students continue to draw around other potato slices in order of size, making sure to line up the center hole each time with the mark on their paper.
5. Students write numeric values on their contour lines, and make every 5th or 4th line (depending upon their scale) darker.
6. Determine from drawn contour maps the steepest slopes, valleys, and likely areas of water run off and stream headwaters. Check choices by putting back together the sliced potato halves.
7. Measure each potato "mountain," and determine the ratio of actual inches to the feet of elevation on students' potato contours. Apply the ratio to create a "map" scale.

A fun exercise for students might be to draw the teacher's face--or that of another student--as a topographic map. If you are studying topographic mapping during the winter with snowfall, another fun exercise is for two groups of students to each build "mountains" out of snow in different areas of the school yard. Each group buries a treasure in their snow mountain. Then they produce a topographic map to scale of what they built (but without compass orientation), marking the location of the treasure with an "X." When finished, each group is timed as they read the map of the other group and find their buried treasure. (Students quickly learn the importance of compass symbols on maps, how easily lost one can become when all slopes look the same, or that an "X" placed on a perfectly sheer vertical face cannot reveal the depth of a treasure.)
 

---

Return to October
Return to Site Map - Calendar