Equipping the Next Generation for Active Engagement in Science Man or machine (1 of 2)

How has cycling changed? How has cycling changed? Use the images to briefly discuss how cycling has changed in the last 50 years. Students may mention the difference in the bikes, clothing, helmets and the way the cyclists cycle very close together (this technique is called drafting and it is used to reduce air resistance). Ask them how they think the speed of cyclists has changed. © Wikimedia Track cycling Colombia: Werner Otto 2 Engage Review Consider

Can bike design give cyclists an unfair advantage? © wikimedia.org Bradley Wiggins Engineers design the bikes which help teams win. But... Can bike design give cyclists an unfair advantage? Introduce the dilemma in this sequence. 3 Engage Review Consider

Learning objectives Contact forces Lesson 1 Describe factors which affect the size of frictional and drag forces Contact forces Lesson 2 Evaluate a claim about how bike design gives cyclists an unfair advantage Critique claims The objectives for the lesson. Big Idea Working Scientifically

Critique claims Use scientific evidence How does engineering make cycling faster? Lesson 1 Use scientific evidence to answer Can bike design give cyclists an unfair advantage? Lesson 2 Critique claims to answer How the students will use scientific evidence in lesson 1 and critique claims in lesson 2 to help them to make a decision. Engage Review Consider

Imagine you’re an engineer for the GB track cycling team You want to increase the cyclists’ top speed. What forces do you need to consider? Ask pairs to discuss the question. 6 Engage Review Consider Engage Review Consider

How can we increase the resultant force and top speed? Air resistance (drag) Name the forces Thrust from cyclist Ask students to work in pairs to name the forces shown by the arrows on the diagram. Reveal the answers and discuss the forces to check previous knowledge before moving on. Explain how the forces are unbalanced, so the resultant (net) force is forwards so the cyclist is speeding up. Discuss how the air resistance will increase as her speed increases because more air particles hit her so to increase the resultant force and top speed we can increase thrust (through training) or decrease drag and friction. Ask the class if they have any ideas how this can be done. Friction 7 Engage Review Consider Engage Review Consider

How can we increase the resultant force and top speed? Reduce drag by... ...reducing the area in contact with the air 1 ...enabling the air to flow easily over the object (streamlining) 2 large area streamlined shape small area Direction of motion Reveal the methods of how to reduce drag and the science behind them. turbulent air forms behind and slows down the object no turbulent air 8 Engage Review Consider Engage Review Consider

How can we increase the resultant force and top speed? Reduce friction by... ...reducing the area of objects in contact with each other 1 ...making their surfaces smooth 2 Reveal the methods of how to reduce friction and the science behind them. You can use oil to smooth surfaces 9 Engage Review Consider Engage Review Consider

How does engineering make cycling faster? SS1–3 How does engineering make cycling faster? Choose clothing, a bicycle frame and wheels to help them cycle faster. Explain how they will help the team to win. Use ideas about drag and friction in your explanation. The task is introduced. Ask students to work in small groups and give each group copies of SS1-3. Their task is to help the cyclists on team GB to cycle faster. They choose clothing, a helmet, (SS1), a bicycle frame (SS2) and wheels (SS3) to build a cyclist and their bicycle. Groups will need scissors and glue. Students then work alone to justify their choices. They should write down their choices for the cyclist and bicycle and explain why they chose them using ideas about drag and friction. Gather information from each group to show which choices they made. This can be done very quickly as a show of hands for each option. Record the most popular choices and explain that this design will be submitted to the UCI who are the ruling body in international cycling. NB: the best options are: helmet B, clothing B, bicycle frame C, rims C, tyres B. Make sure that these choices are the ones that are submitted! 10 Engage Review Engage Review Consider

Man or machine? Student sheets Sheet no. Title Notes SS1 Clothes Consumable, one per group SS2 Bicycle frame Consumable, enlarge to A3, one per group SS3 Wheels

Clothes 2 1 Helmet Clothing  A B C A C B SS1 Choose the helmet and clothes. Cut them out and stick them on the cyclist. Cut out the cyclist. 1  Helmet A B C Clothing A Loose fitting shorts and top C Tight fitting shorts and top B Tight fitting lycra bodysuit

Cycling position when this frame is used SS2 Bicycle frame Choose your frame and cut it out. Use the cycling positions to help you choose which would reduce drag the most. A side front With drop handles Cycling position when this frame is used B With aerobars Tucked position C

Wheels A A B B C C Rims Tyres SS3 Wheels Choose your tyres and rims. Cut them out. Stick the rims onto the tyres and then onto the bike. Rims Tyres Thin tyres with treads A Lots of spokes A B B Thin, smooth tyres – no treads Three spokes No spokes (disc wheels) C Thick, heavy tyres with deep treads C Spokes cause turbulence as the air travels through them Treads increase grip on the ground

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Equipping the Next Generation for Active Engagement in Science TRACES