Teaching A2 Physics Practical Skills (pdf document) free file download at fliiby.com

"Teaching A2 Physics Practical Skills Teaching A2 Physics Practical Skills Contents Introduction Why should I read this booklet? How much teaching time should I allocate to practical work? Can I use the practicals in these booklets in a different order? What resources will I need? Is there a limit to the class size? Why should I teach my students practical skills? Points to consider What are the practical skills required by this course? Summary of each of the seven skills A sequence for introducing the skills Ways of doing practical work Keeping records How is a practical activity organised? Teaching A2 skills The feel of practical work in the A2 year Extending AS practical skills for the A2 year Teaching students to plan experiments Teaching students to evaluate conclusions Designing a practical course for the A2 year Planning the course Using past exam papers Planning lessons and teaching the course Planning for a circus Appendix 1: Possible A2 practical activities Appendix 2: Examples of A2 practicals Newton’s Law of Cooling Specific Heat Capacity of Oil Specific Latent Heat of Vaporisation of Water Discharge of a Capacitor Investigation with a Hall Probe Force on a Current-Carrying Wire Behaviour of a Light-Dependent Resistor The Temperature Characteristic of a Thermistor The Operational Amplifier as an Inverting Amplifier Cantilever Investigation Appendix 3: Useful resources 1 1 1 1 2 2 3 3 5 5 7 9 12 13 15 15 15 16 19 23 23 24 24 25 26 39 40 44 49 54 58 63 67 71 76 81 86 Introduction You may have been teaching AS and A level physics for many years or perhaps you are new to the game. Whatever the case may be, you will be keen to ensure that you prepare your students as effectively as possible for their examinations. The use of a well-structured scheme of practical work will certainly help in this ambition. However it can do so much more. Science students who are thoroughly trained and experienced in practical skills will have a ‘feel’ for the subject and a confidence in their own abilities that is far greater than that of students with a purely theoretical background. It is true that there are branches of physics that might be described as purely theoretical but they are in the minority. Essentially, physics is an experimental subject and we owe it to our students to ensure that those who pursue science further have the necessary basic practical skills to take forward into their future careers. Furthermore, the basic skills of planning, analysis and evaluation will be of great value to those who pursue non-science careers. Why should I read this booklet? You may be wondering why you should need a booklet like this. If your practical skills are of a high order and you feel confident teaching these skills to others, you probably don’t need it (although you might find some of the exercises described in the appendices useful). However, if you are like the majority of us, a little help and support is likely to be appreciated. This booklet aims to provide at least some of this support. The booklet is designed for the teacher, not for the student. Its objective is to provide a framework within which teachers can develop their confidence in teaching practical skills. Experience suggests that as this confidence grows, the time that teachers are prepared to spend on teaching practical skills also grows. How much teaching time should I allocate to practical work? The syllabus stipulates that at least 20% of teaching time should be allocated to practical work. This is in addition to any time the teacher chooses to use for practical demonstrations to illustrate the theory syllabus. This emphasis on practical work is not misplaced. If the specific practical papers (papers 3 and 5) are considered in isolation, they represent 23% of the examination. However, practical work is not merely a necessary preparation for the practical papers. Questions in the theory papers may also assume an understanding of experimental data or practical techniques. The theory papers also give a considerable weighting to the skills of handling, applying and evaluating information, and one of the ways in which students acquire these skills is through their course of practical work. In planning a curriculum, teachers should therefore expect to build in time for developing practical skills. If, for example, the time allowed is 5 hours per week over 35 weeks, then a minimum of 1 hour per week should be built into the plan, so that over the year, a minimum of 35 hours is made available. Bearing in mind the weighting given to assessment objectives that relate to information handling and problem solving, 35 hours should be regarded as an absolute minimum. Can I use the practicals in these booklets in a different order? It is assumed in these booklets that for A level candidates, the AS work will be taught in the first year of the course, with the A2 work being covered in the second year. If the linear A Level assessment route is used, care should be taken with regard to the order in which practical exercises are used, as the skills practiced in these booklets are hierarchical in nature, i.e. the basic skills established in the AS booklet are extended and developed in the 1 A2 booklet. Thus, students will need to have practiced basic skills using AS exercises before using these skills to tackle more demanding A2 exercises. The exercises in these booklets are given in syllabus order. A teacher may well decide to use a different teaching sequence, but the point made above regarding AS and A2 exercises still applies. What resources will I need? For a practical course in A-level physics to be successful, it is not necessary to provide sophisticated equipment. Some of the more advanced practicals in these booklets may require less easily obtainable equipment, but the vast majority can be performed using the basic equipment and materials in the laboratory. A list of basic resources regularly required for assessment may be found in the syllabus. A more detailed list of apparatus suitable for teaching purposes may be found in the CIE booklet ‘Planning For Practical Science in Secondary Schools’. Is there a limit to the class size? There is a limit to the class size that is manageable in a laboratory situation, particularly when students may be moving about. The actual size may be determined by the size of the room, but as a general guide, 15 - 20 students is the maximum that one teacher can reasonably manage, both for safety reasons and so that adequate support can be given to each student. Larger numbers would require input from another person with appropriate qualifications, or alternatively would require the class to be divided into two groups for practical lessons. 2 Why should I teach my students practical skills? Although this section is likely to be read once only, it is arguably the most important, for if it convinces some readers that practical work is an essential part of physics and underpins the whole teaching programme, one of the aims of publishing this booklet will have been achieved. Points to consider • It’s fun! The majority of students thoroughly enjoy practical work. The passion that many scientists have for their subject grew out of their experiences in practical classes. Students who enjoy what they are doing are likely to carry this enthusiasm with them and so be better motivated in all parts of the course. Learning is enhanced by participation as students tend to remember activities they have performed more easily, thus benefiting their long-term understanding of the subject. Students who simply memorise and recall facts find it difficult to apply their knowledge to an unfamiliar context. Experiencing and using practical skills helps develop the ability to use information in a variety of ways, thus enabling students to apply their knowledge and understanding more readily. The integration of practical work into the teaching programme quite simply brings the theory to life. Teachers often hear comments from students such as “I’m glad we did that practical because I can see what the book means now.” and “It’s much better doing it than talking about it.” Physics, in common with other sciences, is by its very nature a practical subject – both historically and in the modern world. The majority of students who enter careers in science need to employ at least basic practical skills at some time in their career. A practical course plays a part in developing many cross-curricular skills including literacy, numeracy, ICT and communication skills. It develops the ability to work both in groups and independently with confidence. It enhances critical thinking skills and it requires students to make judgements and decisions based on evidence, some of which may well be incomplete or flawed. It helps to make students more self-reliant and less dependent on information provided by the teacher. The skills developed are of continued use in a changing scientific world. While technological advances have changed the nature of many practical procedures, the investigative nature of practical science is unchanged. The processes of observation, hypothesis formation, testing, analysis of results and drawing conclusions will always be the processes of investigative science. The ability to keep an open mind in the interpretation of data and develop an appreciation of scientific integrity is of great value both in science and non-science careers. Practical work is not always easy and persistence is required for skills and confidence to grow. Students often relish this challenge and develop a certain pride in a job well done. The more experience students have of a variety of practical skills, the better equipped they will be to perform well in the practical exams, both in terms of skills and confidence. Some teachers have argued that the skills required for Paper 3 can be developed simply by practising past papers; however, experience suggests that this approach does not usually produce good results, and that confidence in practical work will be greatly enhanced by a wider variety of practical experience. Similarly for Paper 5, it might be argued that planning, analysis and evaluation could be taught theoretically. However, without hands-on experience of manipulating their own data, putting their plans into action and evaluating their own procedures and results, students will find this section difficult and will be at a distinct disadvantage in the examination. Those students who 3 • • • • • • • achieve the highest grades do so because they can draw on personal experience, and so are able to picture themselves performing the procedure they are describing, or recall analysing their own results from a similar experiment. Students with a bank of practical experience are much more likely to perform well than those with limited practical skills. 4 What are the practical skills required by this course? The syllabus specifies the practical skills to be assessed by providing generic mark schemes for the practical papers. These mark schemes divide practical skills into four broad areas. • • • • Manipulation, measurement and observation Presentation of data and observations Analysis, conclusions and evaluation Planning AS AS AS and A2 A2 For teaching purposes, it is helpful to subdivide the first and third of these broad areas into slightly narrower ones. Students will also find it helpful to think about the sequence in which practical skills are used in a typical scientific investigation. This course addresses practical skills under seven headings that contribute to the overall understanding of scientific methodology. In a scientific investigation these would be applied in the following sequence. 1 2 3 4 5 6 7 Planning the experiment Setting up and manipulating apparatus Making measurements and observations Recording and presenting observations and data Analysing data and drawing conclusions Evaluating procedures Evaluating conclusions It is easy to see how these seven skills are related to the four areas in the syllabus. The emphasis of the AS part of the course is on skills 2, 3, 4, 5 and 6. In other words, students have to master the basic skills of manipulating apparatus, making measurements, displaying their data in tables and on graphs, and drawing conclusions. They also have to learn to critically evaluate the experimental procedures by identifying limitations and sources of error and by suggesting improvements. The A2 syllabus concentrates on skills 1, 5 and 7 – the higher-level skills of planning, data analysis and evaluation. All of the skills developed in the AS part of the course are assumed to have been mastered and skill 5 is extended and deepened. The A2 skills can only be developed by allowing students to take a greater degree of control over the procedures they use in practical classes. Summary of each of the seven skills Full details of the requirements for each of these skills may be found in the syllabus. What follows below is a brief summary of the skills involved. 1 Planning • Defining the problem Students should be able to use information provided about the aims of the investigation, or experiment, to identify the key variables. • Methods of data collection The proposed experimental procedure should be workable. It should, if the apparatus were to be assembled appropriately, allow data to be collected without 5 undue difficulty. There should be a description, including clear labelled diagrams, of how the experiment should be performed and how the key variables are to be controlled. Equipment, of a level of precision appropriate for the measurements to be made, should be specified. • Method of analysis Students should be able to describe the main steps by which their results would be analysed in order to draw valid conclusions. This may well include the proposal of graphical methods to analyse data. • Safety considerations Students should be able to carry out a simple risk assessment of their plan, identifying areas of risk and suggesting suitable safety precautions to be taken. 2 Setting up and manipulating apparatus Students must be able to follow instructions, whether given verbally, in writing or diagrammatically, and so be able to set up and use the apparatus for experiments correctly. They will need to be able to work with a variety of different pieces of apparatus and to work from circuit diagrams. 3 Making measurements and observations Whilst successfully manipulating the experimental apparatus, students need to be able to make measurements with accuracy and/or to make observations with clarity and discrimination. They may need to be able to use specific measuring instruments and techniques, such as Vernier scales, cathode-ray oscilloscopes, or Hall probes. They need to be able to manage their time while they make measurements, and to be able to make decisions about when it is appropriate to repeat measurements. They need to organise their work so that they have the largest possible range of readings and so that the readings are appropriately distributed within that range. They should be able to identify and deal with results which appear anomalous. 4 Recording and presenting observations and data Observations, data and reasoning need to be presented in ways that are easy to follow and that accord with conventional good practice. • Tables of results The layout and contents of a results table, whether it is for recording numerical data or observations, should be decided before the experiment is performed. ‘Making it up as you go along’ often results in tables that are difficult to follow and don’t make the best use of space. Space should be allocated within the table for any manipulation of the data that will be required. The heading of each column must include both the quantity being measured and the units in which the measurement is made. Readings made directly from measuring instruments should be given to the number of decimal places that is appropriate for the measuring instrument used (for example, readings from a metre rule should be given to the nearest mm). Quantities calculated from raw data should be shown to the correct number of significant figures. • Graphs Students should label the axes of their graphs clearly with the quantity, unit and scale all clearly shown in accordance with conventional good practice. Scales should be chosen so that the graph grid is easy to use and so that the plotted points occupy the majority of the space available. All of the points in the table of results should be plotted accurately. Students should be able to draw curves, tangents to curves or lines of best fit. 6 • Display of calculations and reasoning Where calculations are done as part of the analysis, all steps of the calculations must be displayed so that thought processes involved in reaching the conclusion are clear to a reader. Similarly, where conclusions are drawn from observational data, the key steps in reaching the conclusions should be reported and should be clear, sequential and easy to follow. 5 Analysing data and drawing conclusions Students should be able to calculate the gradient and intercepts of a line, including finding the intercepts when a false origin has been used on the graph. They should be able to use these to find the equation of the line of best fit through their points. They should be able to relate an equation predicted by theory to the equation of their line of best fit or to their data, and hence to find the values of constants or to draw conclusions about the veracity of the theoretical prediction. They should be able to use the idea of proportionality in their reasoning. They should be able to make predictions or hypotheses based on their data. In the AS part of the course, students would normally be told what quantities to calculate, what graph to plot and would be led through the analysis. In the A2 part of the course, students would normally be expected to be able to plan the analysis for themselves. This would normally include deciding what quantities to plot in order to obtain a straight-line graph, deciding how to calculate these quantities from their raw data, and deciding how to reach a conclusion from their graph. 6 Evaluating procedures Students should be able to identify the limitations and weaknesses of experimental procedures. To be able to do this effectively, they must have a clear idea of the purpose of the experiment, and they must have carried out the procedure for themselves. They should be able to make reasonable estimates of the uncertainties in the quantities they have measured directly, and to compare these so that they can identify the largest sources of error. They should be able to suggest improvements to the experimental procedure which would improve the accuracy or reliability of the experiment. 7 Evaluating conclusions This skill is primarily concerned with the treatment of errors. Where the outcome of an experiment is the value of a constant, the treatment of errors should lead to an estimate of the uncertainty in the student’s value. Where the experiment is a test of a hypothesis, the treatment of errors should allow the student to discuss the validity of their conclusion in terms of the precision of the experimental procedures. As part of the treatment of errors, students should be able to make estimates of the uncertainties in their measurements, calculate the uncertainties in derived quantities, display error estimates in tables of results, plot error bars on their graphs, and estimate the uncertainties in their calculations of gradients and intercepts. A sequence for introducing the skills The above list shows the seven skills in the order in which they would be used in an extended investigation. It is not suggested that these skills should be taught in this order (although students will find it he..."

You need to upgrade your Flash Player , or try to enable javascript in order see this document properly.