Unit 4E Friction

Expectations most children will: describe some of the factors that increase friction between solid surfaces and increase air and water resistance; describe how to measure forces and describe how to investigate friction, explaining what their results show and relating what they found out to their everyday experience some children will have progressed further and will also: describe situations in which frictional forces are helpful as well as those in which frictional forces resist motion

National Curriculum: SC4 Forces and motion 2c) about friction, including air resistance, as a force which slows moving objects and may prevent objects from starting to move 2e) how to measure forces and identify the direction in which they act

QCA Suggested Activities Extending and enriching activities/questions Show children forcemetres and point out the spring inside them. Ask them to  use a range of forcemeters suggest how they work. Help children to (calibrated in Newtons, range practise reading the forcemeter eg when between 10n and 50n) and another child pulls on it, pulling open a challenge the children to pull drawer, dragging an object across the different forces eg 5n, 7n, 8n etc. floor. Ask children to suggest whether it Hide the scale to see if they can pull would be more or less difficult to get an accurately. object moving on a smooth or rough  children use different forcemeters to surface. Ask children how they might try to pull exactly the same force on answer this question and. If appropriate, each one. demonstrate using a forcemeter attached  predict force then pull various to an object eg a weighted margarine tub objects to check their predictions. or a weighted shoe, how this question might be investigated. Discuss with the children what different forcemeter readings show.

Ask children to investigate on which  children could extend their work by surfaces objects slide most easily. investigating changing surfaces to Present children with at least three allow objects to move more easily different surfaces, and ask them what eg by coating the surface with they think will happen. Help children to different materials such as liquids, decide what to do and how to ensure their Vaseline, chalk etc. test is fair. Ask the children to present  children should make their own their results in a bar chart, helping them suggestions about how they should where appropriate. Discuss with the test their ideas. children the different methods they chose  link this work to everyday uses such to investigate the question, and whether as lubricants in engines, oil on some were better than others for bicycle chains answering the question. Ask children to suggest what this work indicates about surfaces for roads, if cars and bicycles are to be safe and not slide

1 Unit 4E Friction

QCA Suggested Activities Extending and enriching activities/questions

 talk with children about surfaces between  children identify several places which there is a low or high friction and where friction is important in every make a list showing everyday situations day situations. where high friction is helpful eg tyres on  extend the activity by thinking cars and bicycles, goalie gloves, tying about situations where less friction shoe laces and everyday situations where is needed or where it can be a low friction is useful eg skating, problem eg skating, bare patches playground slides on a ski slope etc.

 ask children to describe what it is like to walk through water eg in a swimming pool  extend this activity by comparing and to suggest why it is difficult. Elicit their different liquids e.g liquid soap, ideas about why fish and boats can move orange juice, syrup etc through water. If necessary prompt them  do the shapes fall in a similar way to think about shape. Show children a tall through the air? cylinder filled with water and talk with  make comparisons between air them about what they could do, using this and water resistance apparatus and a small piece of plasticine, to find out which shapes move easily through water. Help children to decide what to measure eg time from dropping the plasticine into the cylinder until it gets halfway down or to the bottom and how to make the test fair eg by always using the same piece of plasticine made into different shapes, always using the same height of water in the cylinder. Ask children to record results in a table and to interpret these in terms of the shape of the object and water resistance. Discuss children’s ideas with them.

 take the children outside and ask them to  extension activities could include run across the playground with a large devising a test with varying sheet of card in front of them. Discuss materials to place on car what they can feel and ask them to try to windscreen, or as a spoiler to see explain what is happening. Extend the the affect of a car travelling down a discussion to riding a bicycle into the wind ramp. (Maybe motorised cars) or walking on a windy day. Demonstrate how the size of the surface affects how fast something falls through the air.

2 Unit 4E Friction

QCA Suggested Activities Extending and enriching activities/questions  ask children to investigate parachutes eg does the size of a parachute affect how  children could carry out long it takes to fall? Ask them what they alternative investigation where plan to measure in order to answer the they use their understanding question. When children have made and about air resistance and recorded some measurements discuss parachute size to help them drop them with the children and help them look objects in a specific order. for patterns in them. Help children to relate (Parachute Challenge) this to their understanding of air resistance.

 use a variety of forcemeters eg  use a forcemeter to measure forces, 2.5N, 5N, 10N, 15N 30N etc. to reading the scale accurately measure the force needed to pull specific amounts. Describe the  explain that a bigger reading on the differences between each forcemeter shows it is more difficult to get forcemeter. an object moving than a smaller reading  find a range of objects to demonstrate differences in force needed to move objects.  explain what they found out in terms of bigger/smaller forces and encourage the use of accurate measurements  explain how the evidence collected answered the question, eg if I have to  carry out test independently, make the slope steeper before it moves making predictions, choosing then the surface stops it sliding; or it will slide best on the surface where the reading variables and recognising fair on the forcemeter is smallest test  carry out a fair test  record accurate measurements  make measurements and construct a bar and construct bar chart to show chart which matches the measurements results  explain their results orally or in writing  make comparisons between eg by saying that the objects slid most results easily on the smoothest surfaces. This is  explain their findings using what I thought would happen results and make conclusions eg the smoother the surface the more easily the object moved  ask children to group different  group surfaces into ‘high friction’ and ‘low surfaces into 'high friction' and friction’ 'low friction' then order them from  given an everyday context eg holding the 'high' to 'low' handlebars on a bicycle or pulling a drawer  find examples of uses friction in out of a desk decide whether it is important every day life and compare these for friction to be high or low to examples of where friction is not useful

Unit 4E Friction

QCA Suggested Activities Extending and enriching activities/questions  describe how they carried out a fair  challenge the children to find a shape test which moves more slowly through  identify which shapes move easily water, exploring a range of shapes to through water and explain this in decide which type of shape works terms of reduction of resistance better than others  explain their results in terms of water resistance  explain in terms of forces why you need to pull hard on a large surface,  ask children to demonstrate examples eg a kite, an umbrella, a sail to hold it of air resistance and report their steady on a windy day eg the air/wind findings to the rest of the class is pushing the umbrella up so I have to pull hard to hold it steady

 describe a fair test eg I used a square  plan and record a fair test on parachute with the same weight each parachutes making accurate time and changed the size of the measurements and using their results parachute to reach conclusions  make measurements of the time taken for the parachute to fall  explain patterns in their results in  use what they have found out to terms of air resistance, eg the largest answer the parachute challenge parachute took longest because it activity trapped most air which stopped it falling quickly

Review work on friction by asking children Review work by asking children to to write and illustrate a story to show imagine what life would be like without how friction is important. Read and friction. Would we be able to sit, walk, run talk about the stories with the etc? Children could write a story about children, the day friction gradually disappeared!