Year 5/6B Spring 1 Science Forces – Welcome to Force-Land

Session 5:Lift an ‘Elephant’ Ride: levers and pulleys
Science curriculum area: Forces / i. explain that unsupported objects fall towards the Earth because of the force of gravity acting between the Earth and the falling object
ii. recognise that some mechanisms, including levers and pulleys, allow a smaller force to have a greater effect
Working Scientifically / i. planning different types of scientific enquiries to answer questions, including recognising and controlling variables where necessary
ii. taking measurements, using a range of scientific equipment, with increasing accuracy and precision, taking repeat readings when appropriate
iii. recording data and results of increasing complexity using scientific diagrams & labels,tables and scatter graphs
iv. using test results to make predictions to set up further comparative and fair tests
v. reporting and presenting findings from enquiries, including conclusions, causal relationships and explanations of and degree of trust in results, in written forms
Teaching Objectives /
  • To investigate how levers work exploring how the position of fulcrum, load and effort impacts on use (Yr5&6).
  • To investigate how pulleys work and how the number of pulleys used changes the effort required (Yr5&6).
  • To draw diagrams that explain the forces, loads, weights and efforts for levers and pulleys (Yr5&6).

Other Curriculum areas / Maths:Use all four operations to solve problems involving measure using decimal notation, including scaling
Teaching Objectives /
  • Scale weights and lengths using appropriate calculations (Yr5&6).

Key Vocabulary:variables, accuracy, precision, causal relationships, gravity, mechanisms, levers, pulleys, transfers, force
Resources
Types of lever, lever investigation guidance& equipment, pulley images, instructions and guidance, and calculations for positioning a fulcrum. / Weblinks
Whole Class:Make some table top seesaws using balsa wood. Explain that the Force-Land development team wants a ride that uses levers and pulleys. Do chn know whatlevers and pulley systems are? Note that levers can help lift a very heavy object using a much smaller force, while pulleys can change the direction a force acts in, making a small input force sufficient to lift a heavy object. Explain that Force-Land wants a ‘lift the elephant’ station where visitors can select the position of the fulcrum in a lever to lift the ‘elephant’, orthey can select one of two pulley systems to do the same. Get chn to try and ‘balance’ a seesaw(a type of lever)using weighted Lego™ figures. Howdid they do it? Now get them to move one Lego person closer to the middle of the seesaw – what happens? (That Lego person goes up – the seesaw is unbalanced, as are the forces). Try again, but this time move the balancing platform (the fulcrum). Can the chn make some generalised statements about what they have just seen (moving one weight closer to the fulcrum has what effect? Moving the fulcrum has what effect?). What is it that causes the seesaw to go down (gravity acting on the Lego figure) - it needs an opposite/resistance force (weight of other figure) to balance it or move it upwards – can Y5 chn suggest a specific enquiry question (Does moving the position of the fulcrum increase or decrease the input force). Then show chn the imagesof the two pulley systems and see if Y5 can again suggest a possible enquiry question. Y6 to then suggest variables and in mixed age pairs make predictions about what they think will happen.
Year 5 & 6 chn to work in mixed age gps of 2 or 3, spending 20 mins on each. Get half of the class to start with the pulley investigations (teacher to work with these gps) then all to swapLever investigation (chn to complete independently): Explain to chn that the ‘elephant’ weighs 100kg and calculations are done on an adult weight of 70kg - get Y6 chn to work out an equivalent ratio and work with Y5s to prep their investigation including variables (see guidance). Explain that a Newton (N) is roughly 10x a kg. Pulley investigation:support chn as they make and test out two pulley systems (see guidance). Encourage chn to experiment with the number of cotton reels used. Y6 chn to complete extension.
Plenary / Get chn to share their ideas and note that while the positioning of the fulcrum is key in this ‘ride’ the weight applied can affect this - increasing the force applied (i.e. more people pushing, although this could get rather crowded!). Note that often in science there may be more than one plausible solution to a problem.Ask chn about their pulley findings and ideas (Y6 to feedback on extension challenge). Look at the mathematical formula for positioning a fulcrum and see if chn can help calculatehow they as individuals could lift a range of heavy objects (e.g. a 65kgadult).H/W spot levers and pulley systems out and about and at home.
Outcomes / Children will
  • Complete a lever investigation, noting how the position of the fulcrum impacts on its effectiveness (Yr5&6)
  • Complete a pulley investigation noting the correlation between effort required the number of pulleys (Yr5&6)
  • Draw diagrams showing the forces, loads, weights and efforts for levers and pulleys (Yr5&6)

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