Bathymetric Mapping and Underwater Ecosystem Health

Sonar and GPS Deep Dive



  • 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.

GPS is a technology that detects radio waves from up to four satellites orbiting the Earth. By detecting tiny differences in these waves, a device with GPS can calculate where we are at all times. 

Sonar is a technology that emits sounds waves that reflect off objects and bounce back to the unit. By timing these reflected sounds and determining their strength, sonar is a way to "see" with sound.

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.