Lesson 1 Taking chances with the Sun

Transcription

1 P2 Radiation and life Lesson 1 Taking chances with the Sun consider health benefits as well as risks that sunlight presents introduce two ideas: balancing risks and benefits, reducing risks revisit the distinction between correlation and cause P2-1 P2.1.1 P2.2.3 P2.2.6 P2.5.2 Begin by looking together at the opening spread for this module, which will be used repeatedly in later lessons. (Note: a) 1 Use Activity AP2.1 Solar UV and your skin to introduce the link between skin colour and UV protection. (Note: b) 2 Use images in Presentation IP2.1 Skin cancer and UV (9 slides), and the Textbook, as the basis for a brief discussion (perhaps in small groups) about: skin cancer (Note: c) geographic and cultural differences in exposure to sunlight. 3 Ask students to read about benefits and risks in Section A in the Textbook, and then answer the questions. Discuss the information about eye cataracts. Check that students remember the language of correlation and cause (factors and outcomes) from the Module C1 Air quality. Ask for (or give) another example that uses these terms correctly. Activity AP2.2 Investigating sun protection products is a class practical that would take a whole lesson in itself. Students use simple UV detectors to qualitatively compare the effectiveness of sun creams rated with different SPFs. Complete Activity AP2.3 Correlation or cause? (H: The second sheet is appropriate for H Tier only.) Textbook: Section A Activity AP2.1 (A G) Presentation IP2.1 Activity AP2.2 (A G) Activity AP2.3 (A G) a The module considers risks and benefits associated with a range of radiations, together called the electromagnetic spectrum. b Skin colour is a personal issue to which some students may be sensitive. It is vital to avoid the suggestion that any skin type is better. It would be wrong to draw attention to individual students who may be embarrassed, especially if they are in a minority. This applies equally to freckled redheads and to black students. c The textbook figures for risk of developing malignant melanoma over a lifetime (1999) are taken from Health Statistics Quarterly, Autumn Office for National Statistics, pp

2 P2-2 P2 Radiation and life Lesson 2 Sunlight and life introduce the terms absorb, reflect, transmitin the context of the Earth s atmosphere explain that photosynthesis adds oxygen to the atmosphere and removes carbon dioxide explain how life on Earth depends on the ozone layer, and how humans affect it P2.1.1 P2.3.1 P2.3.2 P2.3.3 P2.3.5 P2.3.6 Ask Would you get sunburn on a space walk? Brief discussion in small groups. Use this to introduce UV levels in space and the effect of the atmosphere. Main (40 minutes) 1 Students read the Textbook spread Sunlight, the atmosphere, and life. A key idea is that absorption involves transfer of energy to the absorbing material. 2 Students complete Activity AP2.4 Selecting colours to reinforce the idea of selective absorption. (: a,b) End (15 minutes) Use the Textbook to teach about the protective filtering of the ozone layer. (Note: c) Show Presentation IP2.2 The space rainbow (11 slides). Complete the questions at the end of the Textbook spread. Optional: H Tier students could do Activity AP2.5 Light and life under water. Textbook: Section A Activity AP2.4 (A G) Presentation IP2.2 Activity AP2.5 (A G) a This will be more engaging if they have access to a digital camera (and, possibly, a computer with image handling software). If these are not available, then supply them all with copies of a single image to annotate. b A conversation with Art Department colleagues might be valuable. They make much use of selective absorption and reflection. c The ionizing nature of UV will be made explicit later. In this lesson the action of the ozone layer is purely descriptive it absorbs UV.

3 P2 Radiation and life Lesson 3 Radiation journeys introduce infrared radiation as another form of em radiation, beyond visible red develop a model of source (or emission)-journey-detector, where the journey involves processes of transmission, reflection and absorption highlight the fact that detection requires absorption P2-3 P2.1.1 P2.1.4 P Start (10 minutes) Use Presentation IP2.3 Sources of infrared radiation (11 slides) and Video IP2.4 Sources of infrared radiation to draw out and emphasize similarities and differences between infrared and visible radiations. 1 Using the Textbook, show how all detected radiation follows a pattern of source-journeydetection. Diagrams show journeys of light where processes of transmission, absorption and reflection are taking place. 2 To make this concrete, students complete Activity AP2.6 Radiation journeys, a circus of six experiments. (Note: a) 3 Discuss the findings, using key vocabulary. (Note: b) End (5 minutes) Return to the two photographs in Section B of the Textbook. Challenge students to interpret these by using appropriate diagrams. All students: could take one or more photographs using digital cameras, and prepare presentations (with e.g. PowerPoint or posters) on the roles of emission, transmission, reflection and absorption, including selective absorption, in photography. Complete the questions at the end of the Textbook spread. F: Activity AP2.7 Sources and detectors of radiation. Textbook: Section B Presentation IP2.3 Video IP2.4 Activity AP2.6 (A G) Activity AP2.7 (A) a They identify the source, journey and detector for different types of radiation. A recording sheet is provided. b As well as radiation, the important terms are: spectrum, emission, transmission, reflection, absorption, filter (selective absorption), frequency. (Frequency is simply used to distinguish different radiations a formal definition is not needed.) Other key points: The radiations are all part of a single family while sound, for example, is something altogether different. Again, the opening spread for this module provides a useful reference, showing the full spectrum. Most of the radiations are invisible but their effects can be made visible and/or can be detected in other ways.

4 P2-4 P2 Radiation and life Lesson 4 Absorbing electromagnetic radiation compare two ways that energy is transferred to absorbers heating and ionization introduce the photon and use the concept to explain why only some radiations have enough energy to ionize atoms P2.1.2 P2.1.3 P2.1.5 P2.1.8 P2.1.9 P2.2.3 P Start with a puzzle: Being inside a microwave oven is like standing in a city street. How? Explain that both places are bathed in electromagnetic radiation (the oven in microwaves, the street in radio waves and microwaves). Ask: Why are you safe in the street? What differences are there between electromagnetic radiations? 1 Use Presentation IP2.5 Absorbing energy, and the Textbook, to discuss and explain the key points. (Note: a) 2 Demonstrate Activity AP2.8 Experiments with radiation to compare energy transfer by gamma radiation and microwave radiation. 3 Students match the information with the spectra shown on the opening spread for this module. Get them to draw a spectrum, and add labels to show which parts of it are particularly associated with each type of energy absorption. Discuss the questions at the end of the spread. (Note: b) Complete the relevant Workbook exercise. Textbook: Section B Presentation IP2.5 Activity AP2.8 (A G) a Electromagnetic energy transfers energy from source to absorber, and often the only effect is heating of the absorber. (The main effect from the em spectrum below visible is to warm things up. And the lower the photon energy the less the heating effect.) Radiation is emitted and absorbed as photons. UV transfers energy to skin, but heating is not the only effect. An individual collision between a photon and an atom can ionize the atom, if the photon is sufficiently energetic. b For the remainder of the module you will be using these absorption mechanisms as explanations.

5 P2 Radiation and life Lesson 5 Microwave safety explain how microwave radiation is able to heat by inducing vibrations explain the idea of intensity, (H: intensity falling with distance) examine the balance of risks and benefits associated with use of microwave ovens P2-5 P2.1.4 P2.1.6 P2.1.7 P P P2.2.1 P2.2.5 (part) P2.5.2 (part) Ask lots of quick questions: How many of you have a microwave oven in the kitchen? Is it used every day? How do you use it? Are there foods that you cannot prepare in microwave ovens? 1 Use Activity AP2.9 Microwave oven experiments to demonstrate penetration and heating effects of microwaves. Accompany this by (or follow with) Activity AP2.10 Microwave oven hazards. 2 Students read the spread in the Textbook, (discussing and) answering the questions. 1 Ask students, in small groups, to jot down benefits and risks of using microwave ovens. 2 As a whole class, draw a see-saw diagram, labelling one side risks and the other benefits. It should become obvious that benefits outweigh any risks. Complete Activity AP2.11 Microwave applications. Textbook: Section C Activity AP2.9 (G) Activity AP2.10 (A G) Activity AP2.11 (A G)

6 P2-6 P2 Radiation and life Lesson 6 Using mobile phones show and explain effects of mobile phones in terms of absorption of microwave radiation describe mobile phone use as striking a balance between benefits and possible risks, and explain why there are uncertainties about safety H: introduce the precautionary principle P2.1.4 P2.1.6 P2.1.7 P P P P2.2.1 P2.2.2 (part) P2.5.2 (part) Read together the (Textbook) UK report on mobile phone safety, January Ask: What is known about effects of radiation from mobile phones? Main (40 minutes) 1 Show the demonstration in Activity AP2.12 Mobile phones as microwave sources. Students record results on the sheet provided. (Note: a) 2 Return to the Textbook spread. Students read about mobile phones and do the relevant questions. End (15 minutes) 1 Discuss the benefits of using mobile phones, and possible risks. (Note: b) 2 H: Explain the precautionary principle. See above. Complete Activity AP2.13 Survey of mobile phone use. Textbook: Section D Activity AP2.12 (A G) Activity AP2.13 (A) a Here is one attempt to describe a mechanism by which microwaves might interfere with body chemistry: news/free/cw00404n012a.htm b If students did AP2.11 Microwave applications as homework, you could compare benefits and risks.

7 P2 Radiation and life Lesson 7 Health studies review the concept of non-ionizing radiations in the context of mobile phone networks explore issues of cause and correlation in studying health and hazards and in decision making explain how to judge a study based on a sample population P2-7 P2.1.4 P2.1.6 P2.1.7 P P P2.2.1 P2.2.2 P2.5.2 Demonstrate Activity AP2.14 Weird or wonderful? to introduce the question, How might you know of a risk that shows no immediate health effect? 1 Introduce the activity with a local story about public fears of radiation from mobile phone masts. The question is: How do scientists study health effects of mobile phones? (Note: a) 2 Students complete Activity AP2.15 A safe place to live? This shows why both sample selection (matching) and sample size are important. Follow up with relevant reading and questions in the Textbook. 3 OPTIONAL: Activity AP2.16 Microwave radiation near phone masts is a short data analysis exercise that could lead to discussion. Nothing is completely safe. Challenge students to produce examples that illustrate this statement. H: Photocopy the mock newspaper article (Storm over mobile phone mast) in the Textbook and ask students to annotate it, using their knowledge of the em spectrum, together with ideas about risk, correlation and cause. Alternatively, give them a real leaflet to annotate such those produced by the Department of Health, or mobile phone manufacturers. Textbook Section D Activity AP2.14 (G) Activity AP2.15 (A G) Activity AP2.16 (A G) a Useful background for the teacher, explains key ideas in epidemiology: ultranet/biologypages/e/ Epidemiology.html

8 P2-8 P2 Radiation and life Lesson 8 X-ray safety use the context of medical X-rays to review the concept of ionizing radiations the idea of making decisions by balancing risks and benefits H: present risk data in different ways and explain the ALARA principle P2.1.2 P2.1.3 P2.1.4 P2.1.5 P2.1.6 P2.1.8 P2.1.9 P2.2.3 P2.2.4 P2.2.6 (part) P2.5.2 (part) Some opening questions: Has anyone recently had an X-ray? At the dentist? A broken bone? Are X-rays safe? Why did the health worker leave the room when you were exposed? Textbook: Sections B, C 1 Students read about X-rays in the Textbook spread and do the relevant questions. 2 Students complete Activity AP2.17 Using X-rays. (Note: a) Activity AP2.17 (A) 1 H: Discuss and explain the ALARA principle. 2 Introduce the homework activity. Encourage students first to look back at the opening spread for this module, and then to find other relevant pages relating to benefits (and risks where appropriate). See above. Complete Activity AP2.18 Spectrum benefits. Activity AP2.18 (A) a Sheet 1 (F/H Tier) explores X-ray risks and benefits in specific contexts. Sheet 2 (H Tier only) asks students to show risk data in a graphical form there will be many creative ways of doing this.

9 P2 Radiation and life Lesson 9 The greenhouse effect introduce the topic of global warming discuss why understanding climate requires long-term weather data, and not anecdotal evidence explain the greenhouse effect in terms of selective absorption of photons P2-9 P2.3.1 P2.3.2 P2.3.4 P2.4.1 P2.4.2 (part) Start (10 minutes) 1 Use the Textbook to introduce the topic. Questions to ask: What does global warming mean?, What evidence is there of global warming?, Is it caused by human activities? (Note: a) 2 Check that students understand the difference between weather and climate. Main (40 minutes) 1 Use the Textbook and demonstrate Activity AP2.19 Physical models of the Earth s radiation to explain the greenhouse effect. (Note: b) 2 Using Animation IP2.6 The greenhouse effect, students complete Activity AP2.20 The greenhouse effect. 3 Make the following key points. (Note: c) the greenhouse effect itself is not a bad thing it is essential to life on Earth. the heating effect of the atmosphere results from tiny amounts of a few gases. Quiz students on the key words: climate, weather, Earth s average temperature, atmospheric CO 2, historical temperature records (and, at H Tier, its proxies), greenhouse effect, greenhouse gases. (Note: d) H: Some key environmental factors are changed by the Earth s average temperature and in turn affect it (e.g. cloud cover, snow and ice, oceans dissolving CO 2 ). Which of these accelerate global warming (positive feedback), and which slow it down (negative feedback)? Complete the relevant questions in the Textbook. Textbook: Section E Activity AP2.19 (G) Animation IP2.6 Activity AP2.20 (A G) a You can download the Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC), published in 2001, from the website: The IPCC does not carry out research nor does it monitor climate-related data. It bases its assessment on peerreviewed and published scientific and technical literature. b Stress the link between the greenhouse effect and the electromagnetic spectrum. Leave discussion of possible consequences of an enhanced greenhouse effect (global warming) to a later lesson. c (if necessary) The atmosphere does not respond the same way to solar infrared radiation and infrared radiation from the Earth it absorbs more of the Earth s radiation (containing less energetic infrared photons). d In advance of the next lesson (carbon cycle), check that you will be able to collect CO 2 produced by Elodea.

10 P2-10 P2 Radiation and life Lesson 10 The carbon cycle explain the carbon cycle and how human activities affect it (Note: a) P2.3.2 P2.3.3 P2.4.3 P2.4.4 Start (10 minutes) 1 The interdependence of living things - a key theme from KS3. EITHER use a good image to illustrate this OR ask students, in small groups, to brainstorm what might be a good image. 2 Refer back to Module C1 Air quality and the conservation of atoms in chemical reactions. (Note: b) 1 Demonstrate Activity AP2.21 Plants use carbon dioxide. (Note: c) 2 Demonstrate Activity AP2.22 Carbon-based life to introduce the more general idea of recycling carbon. 3 Check the outcome of the Elodea experiment. Students make a record using the sheet for Activity AP2.21 Plants use carbon dioxide. End (5 minutes) Use the Textbook and show how human activities are moving carbon atoms from the fossil fuel reservoir to the atmosphere. Students complete the textbook questions about the carbon cycle. Complete the relevant workbook exercise. Textbook: Section E Activity AP2.21 (A G) Activity AP2.22 (G) a Other free activities explaining the carbon cycle are available at: learnnet/jesei/indx2.htm Search for animated carbon cycle on the Web and you will find a variety of useful animations, pitched at different levels. Cache one or more of these so that you run them offline, as the basis for a quiz or review. b It will help students to grasp the abstract concept of the carbon cycle if they think concretely about what happens to particular atoms. c The Guidance for this demonstration contains a story about 2 carbon atoms, which you may want to photocopy and discuss after looking at the outcome of the Elodea experiment.

11 P2 Radiation and life Lesson 11 Changing climates? possible consequences show the links between lifestyles, carbon emissions, and global warming H: explain why, to estimate the risk associated with a hazard, you need to consider both the chances of something happening and the consequences if it does P2-11 P2.4.5 P2.4.6 (parts) Start (10 minutes) EITHER set the scene with Presentation IP2.7 Chris Reid on ocean changes. (Note: a) OR get straight on with the main activities. Main (40 minutes) 1 Show Presentation IP2.8 CO 2 and my lifestyle, a questionnaire for students, which will help them estimate their environmental impact, including CO 2 emissions. (Note: b) 2 F: Students read about predicted effects of global warming, in the Textbook. Support them in answering questions 1 and 2. H: Use either Activity AP2.23 The IPCC statements of risk, or the Textbook, to introduce the idea that risk assessments must take account of both the chances of something happening the consequences if it does. F: Return to the greenhouse effect and greenhouse gases to help them remember the causal link between atmospheric CO 2 and global temperatures. H: Use Presentation IP2.9 Climate modelling to explain how they are used to make climate predictions. (Note: c) See above and below. H: Complete Activity AP2.24 Global warming evidence past and present. Textbook: Section F Presentation IP2.7 (G) Presentation IP2.8 (G) Activity AP2.23 (A G) Presentation IP2.9 Activity AP2.24 (A G) a This presentation considers changes in plankton populations. Guidance notes contain an accompanying transcript. Phyto-plankton is responsible for about half of the Earth s photosynthesis. b The accompanying Guidance outlines a possible follow-up, which begins by comparing their results with international data. c Students can run a climate model on their home computer. See: The UK Climate Impacts Programme has prepared a set of four climate-change scenarios for the UK, known as UKCIP02. These provide a common starting point for assessing national vulnerability, impacts and adaptation. See: index.html To see the effect of rising sea levels on the UK, use a topographical map alongside this graph: climatechange/cm4913/4913html/i mages/08.gif

12 P2-12 P2 Radiation and life Lesson 12 Changing climates time for action explain that action on global warming requires social choices to be made consider some possible actions to reduce carbon emissions H: consider whether the pattern of increasing CO 2 in the atmosphere and global warming is a correlation or cause (Note: a) P2.4.6 (parts) Show and briefly discuss Presentation IP2.10 Images of climate change? (6 slides). Main (3040 minutes) Consider carefully which ONE of the following options will work best for your students. (Note: b) 1 Students do a role-play for Activity AP2.25 A time for action. 2 Divide the class into small groups. Each group prepares a 4-minute item about global warming for Newsround explaining what it means and what, if anything, can be done to reduce it. Different students judge each presentation, using a proforma, Activity AP2.26 Newsround evaluation 3 Individually or in pairs students complete Activity AP2.27 My view of global warming. (Note: c) There are 2 sheets: F: Students use a writing frame to write a 2-minute speech or letter about global warming to the local MP. H: Students write an article about global warming for the school or local newspaper. End (1020 minutes) Plenary for the Main activity. See above. Complete the Textbook questions. Textbook: Section F Presentation IP2.10 Activity AP2.25 (G) Activity AP2.26 (A) Activity AP2.27 (A) a In this final lesson, students should feel involved and positive about the actions that they can take personally. They should also understand the need for government action. b A fourth option would be to download an activity from: For example, Global meltdown, Day after Tomorrow the prequel, The Day after Tomorrow. c Encourage students to use their textbook and any other information sources, and to include both information and opinion in their article.

13 P2 Radiation and life Cover lesson A Radiation and risk review the different types of electromagnetic radiation, and ways of thinking about risks (Note: a) P2-13 Use the opening spread in the Textbook to remind students of the range of electromagnetic radiations. If they have already had four lessons on this module, they should be able to distinguish between ionizing and non-ionizing radiations. Textbook: Sections AD Students complete Activity AP2.28 Radiation and risk. Activity AP2.28 (A G) Compare and discuss students answers. a Students have been learning about characteristics of the electromagnetic spectrum, and its associated risks. They have also looked for patterns in data and so encountered the distinction between correlation and cause. This lesson revises their knowledge and understanding of these ideas.

14 P2-14 P2 Radiation and life Cover lesson B Global warming challenge review the greenhouse effect, the carbon cycle, and ways of thinking about risks associated with global warming Use the closing spreads in the Textbook to remind students about the greenhouse effect, the carbon cycle and possible sequences of global warming. Textbook: Sections E, F Students complete Activity AP2.29 Global warming challenge. Sheet 3 is for H Tier only. Activity AP2.29 (A G) Go over the answers, consider attempts at corrections, and compare scores.