Lesson overview

The operating depth limit for the submersibles used on the XL Catlin Deep Ocean Survey was 1,000 feet. To put this in context, recreational scuba diving has a limit of 130 feet, but the deepest point in the ocean is an astounding 36,070 feet down.

In this lesson, students investigate the effects of pressure increasing with depth, and the implications that this has for submarine design. Get the design wrong and the submarine will implode.

Learning outcomes

• Describe the dangers of exploring a depth (foundation)
• Explain why pressure increases with depth (developing)
• Design and carry out a fair test to investigate the effects of increasing depth (competent)
• Calculate the amount of pressure caused at different depths (experts) Explain, in terms of forces, why submarines have a safe limit to which they can dive (advanced)

Lesson steps

1. Brief (15 mins)
   Students are introduced to the concept of pressure at depth through a demonstration. The context of designing an investigation into the effects of pressure on submersibles is introduced. Students set themselves targets based on the learning criteria of the lesson.

2. Investigation (30 mins)
   Students follow the investigation brief to try to design and carry out an investigation into the effects of pressure at depth on a submarine’s hull. Students are encouraged to adapt and design their plan through practical trials.

3. Pressure calculations (15 mins)
   Using the slides, students learn how to calculate pressure at depth, and the importance of the submersible’s structure supporting the forces of the water. Students calculate pressure at depth for various contexts, and predict if a submersible will be able to safely dive to a given depth.

4. Self-reflection (5 mins)
   Students decide if they have met their targets set at the beginning of the lesson, and reflect on the lesson’s importance to the context of the Scheme of Work.

England

Key Stage 3 Physics

• Forces: using force arrows in diagrams, adding forces in one dimension, balanced and unbalanced forces
• Forces: gravity
• Forces: associated with deforming objects
• Pressure in fluids: pressure in liquids, increasing with depth; upthrust effects, floating and sinking
• Pressure in fluids: pressure measured by ratio of force over area

Key Stage 3 Working scientifically

• Scientific attitudes
• Experimental skills and investigations
• Analysis and evaluation
• Measurement

USA

NGSS Grades 5-8

• Matter and Its Interactions
  5-PS1-3. Make observations and measurements to identify materials based on their properties.
• Motion and Stability: Forces and Interactions
  5-PS2-1. Support an argument that the gravitational force exerted by Earth on objects is directed down.
• Engineering Design
  3-5-ETS1-1. Define a simple design problem reflecting a need or a want that includes specified criteria for success and constraints on materials, time, or cost.
  3-5-ETS1-2. Generate and compare multiple possible solutions to a problem based on how well each is likely to meet the criteria and constraints of the problem.
  3-5-ETS1-3. Plan and carry out fair tests in which variables are controlled and failure points are considered to identify aspects of a model or prototype that can be improved.
  MS-ETS1-1. Define the criteria and constraints of a design problem with sufficient precision to ensure a successful solution, taking into account relevant scientific principles and potential impacts on people and the natural environment that may limit possible solutions.
  MS-ETS1-2. Evaluate competing design solutions using a systematic process to determine how well they meet the criteria and constraints of the problem.
  MS-ETS1-3. Analyze data from tests to determine similarities and differences among several design solutions to identify the best characteristics of each that can be combined into a new solution to better meet the criteria for success.
• Science and Engineering Practices
  Asking questions
  Developing and using models
  Planning and carrying out investigations
  Analyzing and interpreting data
  Using mathematics
  Constructing explanations
  Engaging in argument from evidence
  Obtaining, evaluating and communicating information