Learning objectives
iThe turning effect of a force depends on the force applied and the distance from the force to the pivot. (green)
iiThe turning effect of a force is called the moment of a force. (red only)
iiiMoment of a force = force х distance. (red only)
ivWhen the two moments/turning effects are unbalanced, a lever will turn.
Scientific enquiry
vDescribe how to balance objects on a beam. (Framework YTO Sc1 9f)
Suggested alternative starter activities (5–10 minutes)
Recap last lesson / Share learning objectives / Problem solving / Brainstorming / Capture interest
Ask a pupil to open the door, pushing near to and far from the hinge. /
  • Explain the turning effect of a force.
  • Use patterns to describe how to balance objects on a beam balance. (Sc1)
/ Set up a beam of wood on the floor or some other simulated ′tightrope′. Pupils walk along it as if it were a tightrope. / Working in pairs, pupils count up the number of pivots in the human skeleton. / Pupils look at a moveable model of the skeleton (if available). Move it to show different pivots.
Suggested alternative main activities
Activity / Learning objectivessee above / Description / Approx.
timing / Target group
C / H / E / S
Textbook L5 / i, ii, iii, iv and v / Teacher-led explanation and questioning ORPupils work individually, in pairs or in small groups through the in-text questions and then onto the end-of-spread questions if time allows. / 20 min / R/G / G / R / S
Activity L5a Paper / i, ii, iii, iv and v / Turning, turningPupils answer questions that give further practice with pivots, levers and turning effects. / 20 min / 
Activity L5b Practical / i, ii, iii iv and v / BalancePupils balance a mass on either side of a beam balance as an introduction to moments. / 15 min /  / ()
Suggested alternative plenary activities (5–10 minutes)
Review learning / Sharing responses / Group feedback / Word game / Looking ahead
Show a balance with two scale pans and how it balances the turning effects of the weights and the object. / Pupils work in pairs using whiteboards to sketch how the turning effect of a forcecan be balanced. / Groups discuss what they discovered about turning effects from Activity L5b. / Play hangman to recap key words. / Show a couple of models of cranes (maybe Lego) with and without a counterbalance.
Learning outcomes
Most pupils will … / Some pupils, making less progress will … / Some pupils, making more progress will …
  • use the relationship between force, area and pressure between solids and within liquids and gases
  • explain the action of levers, including examples in the human skeleton, in terms of the turning effect of a force
  • use the principle of moments to explain balance and give examples of its application, e.g. crane counterweight.
/
  • recognise that the turning effect of a force can be increased by increasing the length of the lever arm and give a use of this
  • describe how to balance a seesaw.
/
  • apply the principle of moments to explain a range of situations, including the action of levers.

Key words / Out-of-lesson learning
turning effect, clockwise, anticlockwise, red only:moment / Homework L5
Textbook L5 end-of-spread questions
Activity L5a

© Harcourt Education Ltd 2004 Catalyst 3

This worksheet may have been altered from the original on the CD-ROM.