Mapping Potato Island

Summary:
Students make a topographic map of a potato. Materials:
  • One potato for each student
  • One clear plastic deli tub for each student
  • Lid of a clear plastic container larger than deli tub
  • Dry erase marker for each student
  • Ruler (cm) for each student
  • Kitchen knife
  • Sharpie marker
  • Blue water (add a little blue food coloring)

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Source:
This classic classroom activity was adapted by Windows team member Dave Mastie to involve one of his favorite teaching aids...the potato!
Grade level:
 5 -9
Time:
20 minutes prep time and 30 minutes class time
Student Learning Outcomes:
  • Students will construct a topographic map of model terrain
  • Students will be able to explain what contour lines are and what they represent.
Lesson format:
Hands-on activity

Standards Addressed:

DIRECTIONS:

Preparation:

  1. Cut one end off of the potato with a kitchen knife to make one side of the potato flat.
  2. Place the potato in the plastic deli tub with its freshly cut flat side facing down. On the uncut, top side of the potato, mark a North arrow (or all cardinal directions) with the sharpie marker.

In Class:

  1. Have student mark a scale on the side of their plastic tub using rulers to indicate one centimeter increments.
  2. Students place the container lid on the deli tub. Tell them to look straight down into the tub and draw a north arrow (based on the directions marked on the potato). Also, draw a circle around the rim of the tub.
  3. Instruct students to remove lid and add blue water carefully until the level reaches the two centimeter mark on the side of the tub. Be careful to not pour the water directly on the potato. Instead pour it towards the side of the tub.
  4. Tell students to replace the lid and orient it with the north arrow on the potato. Draw a line where the water meets the potato. This is the shoreline. Looking straight down and closing one eye helps when drawing the shoreline.
  5. Repeat steps 5 and 6 until there are several contours at one centimeter increments and the potato is submerged. Mark the contour interval (vertical distance between contours) on the lid (C.I.=1 cm)
  6. Remove the lid of the container and place against a white piece of paper to see the resulting contour map of potato island clearly. Do all the potatoes have similarly shaped contours?

BACKGROUND INFORMATION:

A topographic map is often a very large scale map that shows the shape of the land's surface. Contour lines are imaginary lines that connect places of equal elevation. If you were taking a hike along a hillside and not walking either uphill or downhill, you would be walking on a contour line. When contour lines are close together, the slope is very steep. When contour lines are far apart, the slope is very shallow. This type of map is helpful when planning a hike. It is also used when planning the site for a building or the path of a new road.

In this example, the potato represents the irregularity of the land surface. Choose potatoes that have an irregular surface, are not too straight sided (i.e., do not make cliffs to the sea) and will not form overhangs. The surface of the blue water will be flat as long as the plastic tub is not moved, and thus provides a way to see what parts of the potato landscape are the same elevation. Closing one eye will help students draw the contour lines because it eliminates depth perception.

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Last modified February 6, 2009 by Lisa Gardiner.

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