Barriers to learning for 'Forces'

Use these lists to prepare for pupils' common misconceptions and confusions when teaching this strand. These can be built into your scheme of work and addressed throughout the learning journey. The lists below include areas such as 'Identifying, measuring and representing forces' and 'Energy and motion, turning effects and pressure'.

Misconceptions around identifying, measuring and representing forces

Pupils often think that:

  • only animate objects can exert a force – thus, if an object is at rest on a table, there are no forces acting on it
  • a rigid solid cannot be compressed or stretched
  • all forces need objects to be in contact to have an effect
  • friction only occurs between solid objects
  • things fall naturally – no forces are involved; barriers stop things falling
  • gravity stops acting when the object hits the ground
  • there is 'more gravity the higher up you go' because things dropped from higher up suffer greater damage when they hit the floor
  • mass and weight mean the same thing and they are equal at all times
  • mass and volume mean the same thing
  • gravity only affects heavy things
  • gravity only works one way – the Earth attracts the Moon but the Moon does not attract the Earth
  • Earth's magnetism and/or spin create gravity
  • astronauts are weightless in an orbiting spacecraft because there is no gravity
  • magnetic field lines are really there – a magnetic field really is a pattern of lines
  • all metals are attracted to a magnet
  • all magnets are made of iron
  • magnetic poles are always at the end of the magnet
  • larger magnets are stronger than smaller magnets
  • all materials that can be magnetised are magnets
  • objects float in water because they're 'lighter' than water or sink because they are heavier; wood always floats and metal always sinks
  • all floating objects float because they have air in them
  • all objects containing air float
  • there is no/less gravity in water
  • power, work, energy and force all mean the same thing.

Misconceptions and confusions around forces and motion

Pupils often think that:

  • if an object is moving there must be a force acting on it
  • if an object is stationary there are no forces acting on it
  • if a force acts on an object it will inevitably move
  • force is a property of an object; an object has force and, when the force 'runs out', it stops moving
  • acceleration can only occur in the same direction as an object is moving
  • when dropped in a vacuum, heavier objects will reach the ground first
  • falling objects stay at the same speed as they fall
  • opening a parachute during freefall makes the skydiver go upwards
  • rocket propulsion is due to exhaust gases pushing on something behind the rocket.

Pupils often confuse:

  • speed, acceleration and velocity
  • distance–time graphs and speed–time graphs.

Misconceptions around forces and turning effects

Pupils often think that:

  • only equal masses can be balanced on a seesaw
  • the pivot has to be between the two forces that are acting
  • forces only cause changes in speed, not direction
  • when a force makes an object travel on a circular path the object must get faster, i.e. the force must cause a change in speed, not just direction
  • cornering objects are forced outwards by a force called centrifugal force.

Misconceptions around forces and pressure

Pupils often think that:

  • pressure and force are synonymous
  • pressure in liquids and gases can be stronger in one direction than another
  • pressure arises from moving liquids or gases; still gas or liquid cannot exert a pressure
  • moving fluids cause higher pressures
  • liquids rise in a drinking straw because of 'suction'
  • fluid pressure only acts downward.