Lesson Focus

This lesson further develops principles of floating and sinking to young learners. It allows children to explore how boats and ships use the principle of displacement and buoyancy to stay afloat. The activities allow children to experiment with different shapes and design of boat ‘hull’ to see which floats best. It introduces the concepts of displacement and buoyancy in a practical activity. It also introduces the idea of a fair test. It can also be used to encourage children to use the engineering principles of and design, test, and improve.


Full Lesson Plan

Age Levels:

4 – 7


  • All children will experience making and improving model boats.
  • All children will test whether their boat floats, and will have a chance to improve their design if it does not float successfully.
  • All children will encounter and have the chance to practice using vocabulary associated with the topic e.g. float, sink, boat, hull.
  • Most children will understand that the shape of the model boat hull affects whether it floats or sinks.
  • Most children will be able to use their own words to describe the activity, and what they think is happening to allow floating or sinking.
  • Some children will understand that displacement is when the shape of the hull (body of the boat) that they model can displace water (push it out of the way, so the space is filled with air) and this is why it floats (sits at the top of the water, breaking its surface tension). Some children will be able to report on this activity, using their own words to explain the principles involved correctly, (or with minor errors which after the teacher corrects they can eventually explain correctly.)

Anticipated Learner Outcomes

  • I can make a model boat which will float on water.
  • I can describe the body of the boat as a hull correctly.
  • I can talk about the shape the hull of the boat needs to be to float on water.
  • I can predict if a model will float or sink- and explain why it will do so using the idea of displacement.
  • I can explain why my model works because of displacement and buoyancy.

Lesson Activities

This lesson further develops principles of floating and sinking to young learners.


  • Student Worksheet
  • Weighing scales
  • Modelling clay/ plasticine
  • inflatable play pool/ tank or large bowl of water
  • Camera to photograph activity as evidence/ form part of assessment
  • Key vocabulary display with explanations/ pictures
  • Images to prompt/ support discussion

Alignment to Curriculum Frameworks

Curriculum alignment sheet is included in PDF.