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Best Hull Shape

Target Audience
Upper Key Stage 2

Link to the National Curriculum

Sc4 Physical Processes (Forces)

Children should be taught to:

  • Identify the effects of air resistance, water resistance and friction, that act between different surfaces

Sc4. Physical Processes (Forces) Yr 6

Non Statutory Guidance

Children should be taught:

  • that they might explore resistance in water by making and testing boats of differnt shapes

Children should:


  • To enable children to understand that friction occurs everywhere in relation to movement on land water and in the air

Download worksheet

What you need

  • A length of water guttering approx 30 inches (75cms)
  • Two stop ends for the guttering
  • Two guttering supports unless the guttering is flat bottomed
  • Balsa wood shapes
  • Paper clips, dress making pins
  • Cotton
  • Stop watch
  • Recording sheets (see downloads)

What you do

  • See the video clip on the website: www.practicalprimaryscience.co.uk
  • Set up the guttering as seen on the video clip
  • Fill the guttering 3/4 full of water*
  • Cut lengths of cotton for attaching to each shape and attach 3 paper clips to act as the force
  • Give the children the recording sheets and a stop watch to record the time each hull shape to travel the length of the guttering.

* When finished with the water siphon it off to save spillage

Group /Class organisation

  • Split the class into groups of 3 or 4*
  • Tell the children to take turns with the stop watches
  • Insist that all measurements must be made under the same conditions to make it a fair test.
  • Each hull shape can be timed three times and an average (mean) taken
  • Results should be recorded on their individual recording sheets (see downloads)

* Regarding additional help much will depend on the maturity of the children and the past experience they have had of practical work. I f the children do not have this experience only one group at a time should undertake the activity under close supervision

How it works

  • From this practical exercise the children will be able to deduce that less drag on each hull pruduces less fricition and the swifter the hull will move through the water.

Preliminary Activities

  • This would take the form of class or group discussion regarding how the ” first boat” was invented. Most probably it was just a humble log that a person from long ago climbed on when he fell into a swollen river.

Follow up work

  • Once the most streamlined shape has been found, this shape can then be used to discover the best length to hull width can be investigated

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