Topographic Investigation: Map an Underwater Surface

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In this activity, learners create a map of a hidden surface using a "sounding stick" -- a technique similar to how underwater maps were once made. The hidden surface is created using plastic tubing inside of a Teaching Tank (a very narrow tank that is commercially available), and the sides of the tank are covered. A "sounding stick" made from either a dowel or drinking straw is used to measure the depth at 2" increments, and the points are graphed to create a profile map. Learners repeat the activity and reduce the increment (increasing the number of samples) to create a better resolution. Modern echo-based devices like sonar have made this technique less necessary, but it's still useful for understanding sampling and imaging.

Quick Guide

Preparation Time:
5 to 10 minutes

Learning Time:
10 to 30 minutes

Estimated Materials Cost:
Over $20 per group of students

Age Range:
Ages 4 - adult

Resource Types:
Activity, Model


Materials List (per group of students)

  • Teaching Tank
  • Masking Tape
  • Construction Paper
  • Marker
  • Ruler
  • Stiff Wire (Old Hanger)
  • Sounding Stick
  • 3/8-Inch Plastic Tubing
  • Graph Paper
  • Colored Pencils


  • Earth and Space Science
    • Earth Structure
      • Oceans and Water
  • Engineering and Technology
    • Engineering
      • Ocean Engineering
  • Mathematics
    • Data Analysis and Probability
      • Data Collection
      • Data Representation
    • Measurement
      • Units of Measurement
  • The Nature of Science
    • The Scientific Process
      • Gathering Data


To use this activity, learners need to:

  • see
  • touch

Learning styles supported:

  • Involves hands-on or lab activities


This resource is part of:

Access Rights:

  • Free access



  • All rights reserved, American Educational Products, LLC, 1996