Lesson overview

This lesson encourages students to investigate hands-on the property of neutral buoyancy, and to discuss its importance in terms of submarines.

There is a practical investigation to achieve neutral buoyancy for a floating object by adding weight. This session also explores the mathematics of density and buoyancy.

Learning outcomes

• Describe how to make floating objects sink (foundation)
• Make an object neutrally buoyant through experimentation (developing)
• Explain how neutral buoyancy is achieved in terms of forces (competent)
• Calculate the density of a spherical object (expert)
• Calculate the weight required to make a floating object neutrally buoyant (advanced)

Lesson steps

1. Brief (15 mins)
   Students view 360VR panoramas of a submarine dive and answer questions, before being introduced to the aim for this lesson, creating a submarine that is neutrally buoyant. Students set themselves targets based on the intended learning outcomes for the lesson.
2. Investigation (20 mins)
   Students follow the investigation brief to try to make their ping pong ball neutrally buoyant. Students are encouraged to adapt to their results, and make changes as they go.
3. Calculating neutral buoyancy (15 mins)
   Using the slides, students learn how an object becomes neutrally buoyant in terms of forces and displacement. Students calculate the amount of mass needed to make their ping pong ball neutrally buoyant, and conduct the experiment to see if their calculations matched the result obtained. Advanced students may wish to calculate this before their experiment.
4. Summary conversation (5 mins)
   Students demonstrate their learning by tweeting a summary of the lesson, or making an Instagram post.
5. 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 overall unit of work.

England

Key Stage 3 Physics

• Forces: as pushes or pulls
• Forces: using force arrows in diagrams, adding forces in one dimension, balanced and unbalanced forces
• Forces: gravity
• Forces: measured in newtons
• Forces and motion: cause objects to stop or start moving, or to change their speed or direction
• Pressure in fluids: upthrust effects, floating and sinking

Key Stage 3 Working scientifically

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

USA

NGSS Grades 5-8

• Motion and Stability: Forces and Interactions
  5-PS2-1. Support an argument that the gravitational force exerted by Earth on objects is directed down.
  MS-PS2-2. Plan an investigation to provide evidence that the change in an object’s motion depends on the sum of the forces on the object and the mass of the object.
• 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