Bathymetric Mapping and Underwater Ecosystem Health

Lesson ⑥

GPS and Sonar



  • Castable sonar/GPS unit


  • Science Notebook
  • Per Group – Enclosed opaque shoebox with a small opening for a hand to fit through
  • Assortment of items to go into the box (dry pasta, squishy erasers, bouncy balls, etc)
  • What’s in the Box? Map template and sheet (Appendix 7)


Questions to ask:

  • How does your phone know where it is?
  • How does it tell you how to get to a restaurant or your home?

Have them discuss take a few share outs. 


Let them know that it is because of the GPS (Global Positioning System) and the sonar in the unit.


noun : a navigational system using satellite signals to fix the location of a radio receiver on or above the earth’s surface


noun a method or device for detecting and locating objects by means of sound waves sent out to be reflected by the objects

How do these features help us to better understand our underwater ecosystem?

Let students know that today they will be exploring a model of what underwater looks like and developing models of how sonar and GPS work to help them better understand how the castable sonar will work. 

Let students explore the box. Questions to ask:

  • How can you know what’s inside without looking?
  • What could you do to find out?

Tell them they will be modeling sonar by exploring the box without looking inside. They’ll do this by first knocking on the box  or gently shaking it, while listening to see what kinds of sounds the objects inside make to make predictions about what mystery objects are inside the box

Next they will place their hand inside to see to feel what is happening in the box.

Using their indirect observation techniques (hearing and touch) have the students construct a mental model and map of what’s inside. Have them draw their models and/or maps in their Science Notebooks


Questions to ask:

  • How was the model you created like sonar and GPS?  
  • How did your model help you determine what was inside the box?


Questions to ask:

  • How did using different techniques allow you to decide what was inside the box?
  • How did it add details and specific items to you box?


Use the students’ Science Notebook models and/or maps as an assessment tool.