Physics investigations

1. Physics investigations

2. Learning outcomes • analyse roles and effectiveness of practical activities in science • consider how to mitigate the damaging effect of assessed practicals • discuss the design and evaluation of standard experiments suitable for GCSE students • develop a repertoire of physics questions suitable for open-ended investigations • discuss collecting and recording data, ways of improving the quality of data • master a variety of simple measurement techniques used in physics • use a straight line graph through the origin as a test for direct proportionality

3. Defining ‘practical work’ ‘Any teaching and learning activity which involves, at some point, the pupils in observing or manipulating real objects and materials.’

4. Practical work Very diverse in nature and purpose Primary learning objectives: • developing knowledge and understanding of the natural world • practical capability - using scientific equipment or following standard procedures • developing understanding of a scientific approach to enquiry

5. Scientific enquiry The quality of evidence is always of concern. When planning and carrying out practical investigations, pupils need to ask, for example, • Is my method valid? • Can I rely on my data when drawing a conclusion? • Are uncertainties in the measurements small enough? • Does the difference between one measurement and another reflect a real change in the thing being measured?

6. NASA Astronomy Picture of the Day February 7, 1998 COBE was launched in November 1989. By March 1991, the research team saw this pattern emerge in their data, but they could not be sure what was noise and what was real. Possible sources of systematic error were rigorously identified, checked and cross-checked. Only in April 1992 were the team ready to go public.

7. Instruments used in physics • micrometer screw gauge– readings on sleeve (0.5 mm graduations) & thimble (2 x 50): reads to 0.01 mm • callipers– vernier scale divides 1 mm by 10: reads to 0.1 mm VPL’s two simulations can be used for practice. other instruments with vernier scales • travelling microscope • spectrometer

8. Now try this In pairs: 1 Use a micrometer to measure the diameter or thickness of various objects. 2 Use verniercallipers to measure a variety of lengths.

9. Another learning objective Communication skills Pupils need to learn how to: • analyse and present data; • draw conclusions from data; • evaluate the quality of data; • present an account of a practical task.

10. Now try this In groups of three: Investigate the relationship between the distance a ‘hot wheels’ toy car is drawn back and how far it then travels forward. Record and analyse any data that you collect.

11. ‘The language of measurement’ Booklet from Nuffield-ASE Aims: to achieve a common understanding of important terms that arise from practical work in secondary science e.g. ‘accuracy’ and ‘precision’ as used by professional scientists (agreed among international metrology institutes - in the UK, National Physical Laboratory, LGC) Target audience: teachers, ITE and CPD providers, publishers, awarding bodies.

12. Straight line graphs tell a story

13. Straight line graphs tell a story periodic time, T, for a pendulum, length l

14. Boyles’ law Equation: Graph: Plotp against 1/V(dependent against independent variable) Straight line, passing through the origin with gradient =nRT

15. Specific heat capacity Equation: Q is found by using energy = power x time energy = current x voltage x time Equation: Graph: Plot temperature change∆Tagainst timet Straight line, passing through the origin with gradient So

16. Now try this In pairs: What graph you would need to plot to confirm the following relationships? 1 Seafloor spreading hypothesis: separation distance of magnetic stripes, x, increases with age of seafloor, t. 2 Intensity of a light source: I = intensity, x = detector distance from source, k = constant

17. Another set of learning objectives Personal development Practical work can help pupils to: • become more motivated to study science • become more confident and self-reliant • learn something about working effectively with others

19. More effective practical work Characteristics: • the task has a limited number of intended learning outcomes • the task design highlights the main objectives and keeps ‘noise’ to the minimum

20. Two worlds domain of real objects and observable things domain of ideas

21. More effective practical work (2) • Stimulate the pupils’ thinking beforehand, so that the practical task answers a question which the pupil is already thinking about. • If the task requires the pupils to make links between the domain of objects and observables and the domain of ideas, ensure that the structure of the task ‘scaffolds’ their thinking.

22. Open-ended investigations In pairs: Discuss experiments listed on the handout ‘Ideas for investigations at KS4’. Which of them might work with your pupils? what year/class? There is also a different list for A-level Physics.

23. Teaching challenges Various factors constrain opportunities for student investigations. • assessment requirements from some awarding bodies. e.g. affects what teachers value; students can be tempted to copy what others are doing, even when it is ill-advised. • apparatus & technician support available can limit the variety of approaches to investigating a similar question. Conclusion: It may be best to encourage lots of simple, open-ended investigative work at KS3, with the aim of developing practical skills and encouraging scientific thinking – not assessment.

24. Further reading Breithaupt opening chapter ‘Units and measurements’ Robin Millar(2010)Analysing Practical Science Activities to assess and improve their effectiveness. ASE Peter Campbell (ed.)(2010) The language of measurement: terminology used in school science investigations. ASE extracts of both ASE booklets:www.gettingpractical.org.uk/Books.php