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Pearson Edexcel GCSE (9-1) Sciences Term 3 detailed summer planning document

This planning document summarises the lesson ideas and resources contained in the third term of the Edexcel GCSE (9-1) Year 9 Teaching and Learning Support that will form part of ActiveLearn Digital Service.

The document also details the practical activities in the free support and the equipment needed to run them. Core practicals are in italics.

Each lesson in ActiveLearn Digital Service will be supported by:

1 x detailed lesson plan1 x powerpoint with learning outcomes1 x knowledge retention quick fire quiz1 x practical worksheet with student instructions1 x student book spread (sample booklets will be printed)1 x digital resource (video, animation, interactive)Checkpoint teaching and learning support (3 x worksheets, 1 x powerpoint)2 x differentiated homework worksheets1 x set of answers1 x online homework for students

In addition there will be short End of Term summative tests.

To subscribe to ActiveLearn Digital Service please click here.

© Pearson Education Ltd 2015. Copying permitted for registered institution only. This material is not copyright free.

http://www.pearsonschoolsandfecolleges.co.uk/Secondary/Science/14-16forEdexcel/Edexcel91GCSEScience2016/Buy/Buy.aspx#TryBuy1_184433

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Biology Spec points covered Starter options Practical activity Teacher-led activity

CB4a Evidence for Human Evolution

B4.4

B4.5

Describe the evidence forHuman evolution, based onfossils, including:a Ardi from 4.4 million years agob Lucy from 3.2 millionyears agoc Leakey’s discovery offossils from 1.6 million yearsago.

Describe the evidence forHuman evolution based onstone tools, including:a the development of stone tools over timeb how these can be datedfrom their environment.

1) Ask students to think about how humans or other animals might evolve in the future. They could draw a labelled picture to show how humans might change and give a reason why they might evolve in that way.

2) Ask students to jot down what evidence we have for identifying how our ancestors lived in the following periods: 100 years ago, 1000 years ago and 100 000 years ago. Take examples of each and consider the reliability of the different kinds of evidence. Establish the idea that this leads to an incomplete record that scientists are still trying to fill in.

Challenge students to find out more about human evolution.

Ensure that students understand that the huge timescales involved in human evolution mean that the fossil record is full of gaps. It is for this reason that scientists cannot agree on an evolutionary tree for human evolution and various educated guesses need to be made to fill in the gaps. Genetic analysis is helping with the research but due to the degradation of DNA with time this is not a complete answer to the problems of piecing together human evolution.

Digital: Ideas about human evolution video

CB4b Darwin’s theory

B4.2

B4.3

Explain Darwin’s theory of evolution by natural selection.

Explain how the emergence

1) Ask whether if one person in the class gets a cold, everyone will? Elicit the idea that not everyone gets ill.

Divide the class into groups. Each group will get some pasta shapes of different colours (in approximately equal amounts, including green pasta), which

Explain Darwin’s theory of evolution as a series of stages to help students remember what happens. Students


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of resistant organisms supports Darwin’s theory of evolution including antibiotic resistance in bacteria.

Challenge students to explain why not everyone gets the cold and introduce the idea that this is partly due to inherited variation – some people are naturally immune to some colds/diseases.

2) Sketch a normal distribution curve on the board and tell students that it shows variation in beak length in a population of sandpipers. The birds dig with their beaks to find small animals to eat. Ask students to suggest why there are more birds with the middle beak length and very few with either very short or very long beaks. Elicit the idea that conditions in the environment make it easiest for birds with medium beak lengths to survive best:

are models for insects. They design a table in which to record the numbers of each different colour of pasta shape. The shapes are then spread out in an open, grassy area. One student is ‘the bird’ and is given a pair of tongs/forceps. The student has 2 minutes to pick up as many pasta shapes as possible. Students count the numbers of each colour returned and calculate percentages. Students should find that red, orange and yellow pasta pieces are more readily found than green pieces, although this will be slightly dependent on the colour of the grass at the time of doing the investigation.

Students repeat their experiment to improve the repeatability of the data. Students then calculate mean percentages returned for each colour. They then use this data to draw pie charts. Ask them to speculate on the future evolution of this green species if: a) the grass remains green b) the grass turns yellow.

should, though, be aware that the process is continuous. Correct misconceptions as they arise. The most common ones revolve around the idea that the environment directly causes organisms to change. It is worth dwelling on the first ‘stage’ of evolution to ensure that students realise that genetic variation is ever present and that natural selection cannot work if there is no genetic variation to start with.

Digital: Evolution of antibiotic resistence presentation


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Equipment: packets of differently coloured pasta, must contain green pasta pieces as well as other colours (500 g per 4–5 students) (you could use buttons of different colours instead but these are not biodegradable), forceps or tongs, stop watch, pot to collect pasta shapes in, area of grass

CB4c Classification

B4.7 Describe how genetic analysis has led to the suggestion of the three domains rather than the five kingdoms classification method

1) Ask students to suggest how a visitor to the area might be able to find an individual student in a school. Give groups of students 5 minutes to come up with a plan of how the visitor would do this. The groups for a student might be: school > year group > form > workgroup > individual.

2) Show students a natural bath sponge (or image of one). Introduce the idea that the sponge is what remains of the insides of an organism. Ask students if they think

Ask students to sort themselves into two groups and then think of another way of dividing themselves into two or more groups. This process can be repeated a number of times. Ask students to explain their reasoning behind their classification systems each time and suggest which system was the best and why. Elicit the idea that scientists group organisms into large groups based on differences between the characteristics, and these groups are called kingdoms.

Take students through the classification of several plants and animals, showing how the number of organisms in each group gets smaller and smaller and how the similarities between the organisms increase. Ask students to suggest other members of the groups as you work through the classifications. Ensure that students understand that the closer a group is to the genus or species grouping, the more


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it’s a plant or an animal or neither. Ask students to list some features that they would find out more about, in order to be certain whether it was a plant or an animal or whether it belonged to some other kingdom (fungi, protists, bacteria).

closely related the organisms will be and the more similar their DNA will be. Point out that in the past scientists looked at the characteristics that they could see, but today classification is usually done according to how similar the DNA is.

Digital: Classification of kingdoms and domains presentation

CB4d Breeds and varieties

B4.8

B4.10

Explain selective breeding and its impact on food plants and domesticated animals.

Describe genetic engineering as a process which involves modifying the genome of an organism to introduce desirable characteristics.

1) Challenge students to produce a list of useful characteristics for cattle on a UK farm (e.g. good meat, quick growing, produce a lot of milk, docile). Then ask what other characteristics might be useful for cattle being farmed in northern Scotland (e.g. thick fur) or Africa (thin fur, less requirement for water. Establish the idea that new breeds of animals and plant are produced to be the most use in a certain set of

The practical measures the amounts of citric acid in different varieties of the same citrus fruit, which is an important factor for breeders. 1 cm3 of 0.1 mol dm−3 sodium hydroxide will neutralise 0.0064 g of citric acid. If you are using apples the multiplication factor should be 0.067 (for malic acid) or for grapes use 0.075 (for tartaric acid).

There should be obvious differences in acidity between different varieties of fruit.

Detail of some different breeds and varieties of common animals and plants that are farmed for food, and how their characteristics make them suitable for farming in certain locations. Present the characteristics and ask students why those characteristics are suitable.

Digital: Farm breeds and varieties presentation


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environmental conditions.

2) Woolly sheep have been bred to produce a lot of wool. However their long woolly tails trap faeces and mud and become infested with maggots. So farmers ‘dock’ the tails of sheep. It would be easier to farm woolly sheep that had naturally short tails. Ask students how they would breed woolly sheep with naturally short tails.

Equipment: eye protection, different varieties of the same species of fruit (e.g. oranges, limes), preferably sliced in half, fruit juicer/squeezer, 2 pipettes or syringes or small measuring cylinders, burette, clamp and stand, filter funnel, filter paper, small beaker, conical flask, phenolphthalein indicator, 0.1 ml dm–3 sodium hydroxide solution, distilled water Optional: refractometer, accurate balance (for Brix measurements), knife to cut fruits

CB4e Genes in agriculture and medicine

B4.14

B4.11

Evaluate the benefits and risks of genetic engineering and selective breeding in modern agriculture and medicine including practical and ethical implications.

Describe the main stages of genetic engineering including the use of:a restriction enzymes b ligasec sticky endsd vectors.

1) Tell students a plant breeder wishes to produce a new variety of orange. Ask students to come up with a list of useful features for the orange to have. Challenge them to write a series of short bullet points to describe how the variety would be created, using selective breeding.

Students research and think about the benefits and risks of a range of selectively bred/genetically engineered organisms.

Remind students of the overall process of genetic engineering. Use four different colours of individual bricks (to represent bases and base pairing) attached to four longer sections so that a break can easily be made.

Point out the sticky ends and then point


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2) Ask students to design their own GMO. They should clearly state what it can do and why that is useful.

out to students that the same restriction enzyme will always make the same sticky ends. So, the same restriction enzyme is used to cut the plasmid open and to cut out the gene that you want to insert, thus allowing the ends to match up. Extend the idea by pointing out that not all of the required genes will get inserted into the plasmids, because some plasmids in the mixture will simply rejoin their ends. In order to be able to identify bacteria that contain a recombinant plasmid, a marker gene is often added to the desired gene first, before they are both inserted into the plasmid. Then bacteria are tested for the marker and it


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is these ones that the scientists will know also contain the desired gene.

Digital: TBC

CB5a Health and disease

B5.1

B5.2

B5.3

Describe health as a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity, as defined by the World Health Organisation (WHO).

Describe the difference between communicable and non-communicable diseases.

Explain why the presence of one disease can lead to a higher susceptibility to other diseases.

1) Write the words health and disease on the board and ask students to suggest words that could be linked with these, and how they should be linked. Encourage class discussion.

2) Without explaining what you are doing, write the names of a few familiar diseases on the board (e.g. 'flu, measles, mumps) and some that are non-communicable (e.g. asthma, cancer, diabetes). Ask students to work in pairs to suggest a link between all the words, and then to suggest a way of splitting the words into two groups.

Provide data that students analyse to compare communicable and non-communicable diseases. Compare the distribution of new cases of cancer per year with the number of measles cases per year. This will show that the numbers are relatively steady each year for cancer, while those for measles can vary considerably from year to year. This can be related to the fact that measles is communicable while most cancers are not. Then compare the age distribution of people with cancer and with measles. The charts drawn from these will show that the number of cases increases with age for cancer, because it results from the malfunction of cells and the risk of this happening increases with age. However,

Show the relationship between HIV infection and infections with cytomegalovirus, Epstein Barr, human herpesvirus 1 and human herpesvirus 8. Discuss with students which values in the table should be compared to identify whether or not there is a correlation between infection with HIV and with a different virus. Agree that infection with HIV is strongly correlated with infection by cytomegalovirus and Epstein Barr virus. The correlation with human herpesvirus 1 is weaker, and there is a negative correlation (more people without HIV than with) between HIV


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measles is more common in childhood because once you have had it, you become immune and will not catch it again.

infection and human herpesvirus 8 infection.

Digital: Disease correlations presentation

CB5b Non-communicable disease

B5.23

B5.24

Describe that many non-communicable human diseases are caused by the interaction of a number of factors including cardiovascular diseases, many forms of cancer, some lung and liver diseases and diseases influenced by nutrition.

Explain the effect of lifestyle factors on non-communicable diseases at local, national and global levels, including:

a … diet on … and malnutrition, …

b alcohol on liver diseases

1) Revise KS3: carbohydrates, fats, proteins, vitamins, minerals and fibre. Students jot down, for each group, one example of a food that contains that constituent. Then they describe the main function in the body of each of the main constituents. Introduce deficiency diseases.

2) Ask students to jot down as many facts about the effects of alcohol as they can. Use the activity to identify gaps in knowledge and understanding.

Students analyse data related to drinking and deaths from alcohol-related conditions. Students will need to know that death from alcohol poisoning is a short-term result of high alcohol intake, whereas liver disease (including cirrhosis) is a long-term result. So it will take many years for the impact of any health campaign on alcohol to show in the statistic of liver disease.

Demonstrate the importance of the liver in the breakdown of toxic substances in the following way.Place a small piece of fresh liver in a blender with about twice the volume of water, and blend till smooth.

Pour about 1 cm of hydrogen peroxide into a test tube, and explain that this substance is made in many cells as a by-product of many processes. Explain that it is highly reactive and therefore toxic to many cell reactions. Use a pipette to add several drops of liver solution to the hydrogen peroxide and ask students to note what happens. They should


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see a vigorous reaction, releasing gas from the mixture. The gas is oxygen, as the hydrogen peroxide is broken down to oxygen and water – neither of which is toxic to cells.

Explain that the liver breaks down many toxic substances, including ethanol (alcohol), and aldehyde which is a toxic breakdown product of ethanol. So liver cells are more exposed to toxins than other cells, and more likely to be damaged which results in disease. Liver disease is correlated with a wide range of other diseases, including anaemia (blood disease), circulatory diseases, kidney disease, as well as cancer.

Equipment small piece of fresh liver, blender, water, access to fridge (optional), pipette, 3% hydrogen peroxide.


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Digital: TBC

CB5c Cardiovascular disease

B5.24

B5.25

Explain the effect of lifestyle factors on non-communicable diseases at local, national and global levels, including:

a exercise and diet on obesity … , including BMI and waist:hip calculations…

c smoking on cardiovascular diseases

Evaluate some different treatments for cardiovascular disease including

• life-long medication

• surgical procedures

• lifestyle changes

1) First run a smoking machine without a cigarette by switching on the pump. After a few minutes, ask students to note the temperature of the air leaving the apparatus, and the colours of the glass wool, indicator solution and limewater. Ask students to suggest what changes may occur with a lit cigarette. Repeat the activity with a lit cigarette in place as shown above. Ask students to describe and, if possible, explain any changes. Emphasise that tobacco smoke contains many substances, and that many are colourless and so not visible. Ask what happens to the substances when the smoke is taken into the lungs. Consider the role of blood in distributing substances around the body.

Students research one of the following treatments for cardiovascular disease:

life-long medication, such as beta-blockers or blood-thinning medicines

surgical procedures, such as bypass or stent surgery

lifestyle changes, such as giving up smoking, increasing exercise and improving diet.

Identify that there are different kinds of cardiovascular disease, such as heart attack (myocardial infarction), stroke, thrombosis, and angina. Students should research the advantages and disadvantages for each kind of treatment, including which kind of patient responds best to that treatment.

Present students with a list of measurements: BMI, waist:hip ratio, heart rate and breathing rate at rest and after a few minutes of simple exercise.

Check that students understand the purpose of measuring BMI or waist:hip ratio, as a simple assessment of the proportion of fat in the body, and why too much fat is a problem. Using yourself or a fit student who won't mind the attention, take measurements of heart rate and breathing rate at rest, after two minutes of gentle exercise and after two minutes of moderate exercise. (Remember to allow raised values to return to resting rates before testing again.) Heart rate can be measured at the wrist or by using a digital


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Equipment: for smoking machine: U tube, bung with single hole and bung without hole (for U tube), 2 test tubes, 2 bungs with 2 holes (for test tubes), thermometer, glass or polymer wool, cigarette without filter, universal indicator solution, limewater, glass tubes and connectors, vacuum pump; fume cupboard.2) Introduce the treatments for cardiovascular diseases in B5.25b of the specification. Ask students to work together to compile the three most important questions they need answers to so they can compare the effectiveness of different treatments.

heart rate monitor. Breathing rate should be measured as the number of breaths taken in 15 seconds. Explain that the heart rate and breathing rate of people who are very unfit and/or obese usually increase more rapidly than those of fitter people. So, the health professional needs to assess what level of exercise is appropriate and safe – too high a rate puts extra strain on the body and may be harmful.

Equipment: stopwatch, digital heart monitor, tape measure, height measurer, bathroom scales

Digital: TBC

CB5d Pathogens B5.4

B5.5

Describe a pathogen as a disease-causing organism including viruses, bacteria, fungi and protists.

Describe some common

1) Write the word 'pathogen' on the board and identify the first part from 'pathos' meaning feelings (i.e. suffer) and 'gen' meaning birth. Ask

Measure the growth of bacteria in fresh milk kept at different temperatures for the previous 24 hours. All samples must be allowed to reach room temperature before the

Explain that less than 200 Cholera was common in cities and was thought to be caused by 'bad air'. Foul smells came from


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infections, including:a cholera (bacteria) causesdiarrhoeab tuberculosis (bacteria)causes lung damagec Chalara ash dieback (fungi) causes leaf loss and bark lesionsd malaria (protists) causes damage to blood and livere HIV (virus) destroys white blood cells, leading to the onset of AIDSf stomach ulcers caused by Helicobacter (bacteria)g Ebola (virus) causes haemorrhagic fever

students what pathogens are and why they were given that name from the root words.

2) Write the names of the four pathogen groups (bacteria, protists, fungi, bacteria) on the board and ask students to write one sentence about each group.

experiment begins. Resazurin dye should be freshly prepared just before the lesson.

The time taken for the dye to become colourless should decrease as temperature increases, because microorganisms generally grow faster at higher temperatures. Equipment: Per student group: access to water bath at 30 °C; 5 test tubes + rack; labelled samples of about 5 cm3 fresh milk, kept in one of the following conditions for 24 hours then allowed to reach room temperature: frozen, 4 °C, 21 °C, 30 °C, 40 °C; about 3 cm3 1% resazurin dye; 1 cm3 syringe; five 10 cm3 measuring cylinders; marker pen for labelling test tubes, watch or clock.

cesspits where human waste collected under buildings before being cleared away. So the correlation between foul-smelling air and disease seemed obvious.

In 1854 there was an outbreak of cholera in London. The doctor John Snow noticed that deaths in his area clustered, and he mapped where the dead people lived. He also asked people in the area where they collected their water (there was no running water then). Show students John Snow's map of deaths and water pumps, and ask them why the distribution of deaths does not support the 'bad air' hypothesis. Ask why the map helps to support the idea that water was the source of the infection.

Digital: John Snow’s © Pearson Education Ltd 2015. Copying permitted for registered institution only. This material is not copyright free.

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map presentation

CB5e Spreading pathogens

B5.6 Explain how pathogens are spread and how this spread can be reduced or prevented, including:

a cholera (bacteria) – waterb tuberculosis (bacteria) – airbornec chalara ash dieback (fungi) – airborned malaria (protists) – animal vectorse stomach ulcers caused by Helicobacter (bacteria) – oral transmissionf Ebola (virus) – body fluids

1) Ask students, individually or in small groups, to make one sentence using each group of three words: bacteria, water, sickness; chalara, air, fungus; Ebola, blood, virus.

2) Remind students of the health advice, usually circulated during winter, of 'catch it, bin it, kill it'. Students should work in pairs to note down how the advice is meant to keep us healthy. They should then consider what the advice would help with and which diseases it wouldn't work for, and why.

The practical investigates the use of toilet paper and hand washing, such as after being to the toilet. Show them how to carry out the method with a single plate and discuss how the approach makes it more likely that results from the experiment can be trusted.Students prepare culture dishes, to allow air to circulate and prevent the growth of anaerobic bacteria. Dishes should be kept upside down, at room temperature for several days.

Prepare malt agar by mixing 2 g malt extract with 2 g agar and 10 cm3 of hot water to make a paste. Slowly stir in more water to a total volume of 100 cm3. Heat the mixture in a boiling water bath to 95 °C, then keep it molten at 50 °C before using standard aseptic technique to pour it into sterile Petri dishes and allow to set and the agar surface to dry. Prepare lawn plates of Saccharomyces cerevisiae on half the agar plates using standard aseptic

There are several ways that you can model the spread of an infectious disease. You could 'prepare' the room before the session by spraying a few areas with a product such as Glo Germ™. Don't warn students that you have done this. Towards the end the lesson, tell students what you have done and explain that this can mimic how pathogens are spread by touch. Use a UV light (which comes with the product) to illuminate not just the areas you sprayed, but other parts of the classroom and students' hands, to identify how far the spray has spread.

Discuss with students which factors could be changed to increase or decrease the time taken for all to become infected, and relate


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technique.This practical is not suitable for students with sensitive skin conditions.

Results can be recorded by drawing, or by measuring the size and number of colonies.

Equipment: per group: 3 lawn plates of Saccharomyces cerevisiae on malt agar, 3 malt extract agar plates, marker pen, sheet of toilet tissue, autoclave bag, dry paper towels, access to soap and warm water for washing hands, sticky tape.

their suggestions to real situations. For example, if the pathogen is not very infectious, then only a small proportion of uninfected people who come into contact with the disease will be infected, and spread will be slow. Digital: TBC

CB5f Physical and chemical defences

B5.1

B5.2

Describe how the physical barriers and chemical defences of the human body provide protection from pathogens, including:

a physical barriers including mucus, cilia and skin

b chemical defence including lysozymes and hydrochloric acid.

Explain how sexually transmitted infections (STIs)

1) Ask students to work in pairs to jot down as many reasons as they can why the clotting of blood is useful when we cut ourselves. Students should identify that the clot prevents further loss of blood, but that it also seals the wound, preventing the entry of pathogens.

2) About a week before

Students investigate the effect of lysozyme in egg white on bacteria. Bacterial lawn plates and egg white dilutions will need preparing before the lesson.

After the first lesson, the plates should be incubated at 20–25 °C for 2–3 days. Make sure students understand that a clear area around a disc indicates where bacteria have been killed.

Link work on lysozyme back to work on enzymes and bacterial structure by asking students what these enzymes might do to pathogens (bacteria). Students should remember that many enzymes catalyse the break down of substances, so lysozymes might break down substances in the


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are spread and how this spread can be reduced or prevented, including:

a Chlamydia (bacteria) b HIV (virus)

the lesson, prepare a bacterial lawn plate using an agar plate and bacterial culture such as Micrococcus. Place an antibiotic disc on the bacteria, tape the base of the dish to the top without sealing it completely and keep the dish warm for the week. Show students the plate, and explain how you prepared it. Say that the paper disc was impregnated with an unknown substance. Ask students to describe the effect the unknown substance has had on the bacteria, and to suggest why it has had this effect. They should identify the clear area around the disc as the area where bacteria have been killed, and that the substance was soluble and spread out from the disc into the agar.

The more diluted the egg white (and therefore the lysozyme in it), the smaller the diameter of clear area around the disc. Results can vary quite widely as it will depend on the initial concentration of lysozyme in the egg white. Using the freshest eggs can help reduce the chance of failure to get a result.

Equipment: per group: one Petri dish with lid of agar covered with a bacterial lawn, egg white in 3 different dilutions (e.g. 100%, 75%, 50%), small discs of filter paper, sticky tape, marker pen, sterile forceps, ethanol (IDA), incubator

bacterial cell wall. Some students may also make the link with osmosis by realising that, if the cell wall weakens, water can continue to diffuse into the bacterial cell. The swelling of the bacterial cytoplasm ay then lead to rupturing of the cell wall (similar to the rupturing of animal cells in solutions that are more dilute than their cytoplasm), and death of the bacterial cell.

Discuss sexually transmitted infections

Digital Sexually transmitted infections video

CB5g The B5.13 Explain the role of the 1) Ask students to work Students investigate looks at Invite a health


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immune system

B5.14

specific immune system of the human body in defence against disease, including:

a exposure to pathogen

b the antigens trigger an immune response which causes the production of antibodies

c the antigens also trigger production of memory lymphocytes

d the role of memory lymphocytes in the secondary response to the antigen

Explain the body’s response to immunisation using an inactive form of a pathogen.

in pairs or small groups to jot down the name of any immunisations/vaccinations they have had as a child or in school. They should then discuss why they had the vaccinations, what they remember about how they work, and to describe what they felt during and after the vaccination.

2) Ask students to think about the last time they had an infection such as a cold, or flu. They should jot down what they remember about why they caught the infection, what happened during the infection and why it went away. Prompt with the idea that only a few pathogens may enter the body, but that conditions inside the body are good for rapid replication. Lead to the answer that it is only when large numbers of pathogens cause harm or changes in the body, that we become aware of

the impact of vaccination rate on infection rate in measles in England and Wales, including the impact of the MMR scare.

professional to a question and answer session with students about vaccinations, including those for sexually transmitted diseases such as HPV, hepatitis A and B. Students should prepare questions before the visit. Encourage class discussion of questions to make sure all the key ones are included, such as how vaccinations work, why they produce immunity, why there aren't vaccinations for all diseases.

Digital Sexually transmitted infections video


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illness.

CB5h Antibiotics B5.16

B5.20

Explain that antibiotics can only be used to treat bacterial infections because they inhibit cell processes in the bacterium but not the host organismDescribe that the process of developing new medicines, including antibiotics, has many stages including discovery, development, preclinical and clinical testing

1) Write the word 'antibiotic' in the middle of the board, then give students a minute or two in pairs or small groups to think of related words or terms.

2) Tell students that a new medicine is being developed to help people suffering from a particular disease. Ask students to work in pairs or small groups to jot down the questions that need answering during the development.

Explain to students that many plants contain substances that help protect them against attack by microorganisms. Some of these have been developed into medicines to help treat our diseases. Make sure that students understand that a clear area around a disc indicates where bacteria have been killed.

Bacterial lawn plates and plant extracts will need preparing before the lesson. Suitable extracts include: chilli powder, cinnamon, cloves, fennel, garlic, paprika, pepper, thyme. To make an extract, grind 3 g crushed or ground plant material with 10 cm3 ethanol (IDA) and shake vigorously for 10 minutes. Give each group two of the plant extracts to use. Results for all extracts will need to be compared across the class.

The plates should be incubated at 20–25 °C for 2–3 days.

Clinical trials are a real-world application of the idea of a fair test that students use in their own work. Help students to compare the way they carry out their practical investigations and the way clinical trials by discussing the following aspects:

Trial size/ sample size

Using controls

placebos and 'blind' trials (more able students only)

Digital: TBC


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Measurement of the diameter of the clear area can be done by ruler or measuring against millimetre graph paper. Colonies could be drawn rather than measured.

All of the suggested plant extracts should show some antibacterial effect.

Equipment: per group: one Petri dish with lid of agar covered with a bacterial lawn, two named plant extracts, small discs of filter paper, sticky tape, marker pen, sterile forceps, ethanol (IDA), incubator


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Chemistry Spec points covered Starter options Practical activity Teacher-led activity

CC8 Masses and empirical formulae

C1.43

C1.44

C1.45

C1.46

Calculate relative formula mass given relative atomic massesCalculate the formulae of simple compounds from reacting masses and understand that these are empirical formulaeDeduce:a the empirical formula of a compound from the formula of its moleculeb the molecular formula of a compound from its empirical formula and its relative molecular massDescribe an experiment to determine the empirical formula of a simple compound such as magnesium oxide

1) Write five formulae on the board, including some with brackets, e.g. MgCl2, Li2O, CuSO4, Ca(NO3)2, (NH4)2CO3. Ask students to work out the number of atoms of each element in each formula and to name the compounds.2) Make up some molecular models, e.g. C2H6, C3H6, C4H10, C3H8, CH3COOH and ask students to work out the formula of the molecules from the number of each type of atom. This is the molecular formula. Then dismantle one model into separate atoms and show them the simplest ratio of each atom. This is the empirical formula. Challenge students to deduce the empirical formulae of the other compounds.

Students determine the empirical formula for magnesium oxide.

The empirical formula of magnesium oxide is MgO. It is unlikely that students will get an exact ratio of 1:1. They can suggest reasons for the difference. For example, some of the magnesium oxide escaped when the crucible lid was lifted, the magnesium had not completely finished reacting, magnesium reacts with nitrogen from the air as well as oxygen.Equipment: For each group: Bunsen burner, crucible and lid, emery paper, heat resistant mat, pipeclay triangle, tongs, tripod, about 3 cm length of magnesium ribbon. Students need access to an electronic balance weighing to at least 2 decimal places.

Take the students through worked examples one step at a time.

Digital Relative formula mass and empirical formulae and relative molecular masses and empirical formulae presentation

CC8b Conservation of

C1.47 Explain the law of conservation of mass applied

1) Show the formation of a yellow precipitate of

Students investigate the decomposition of copper

Take the students through worked


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mass

C1.48

C1.49

to:a a closed system including a precipitation in a closed flaskb a non-enclosed system including a reaction in an open flask that takes in or gives out a gasCalculate masses of reactants and products from balanced equations, given the mass of one substanceCalculate the concentration of solutions in g dm-3

lead iodide by pouring small amounts of lead nitrate and potassium iodide solutions in a boiling tube. The final mass should be the sum of the two initial masses. Now add dilute hydrochloric acid to marble chips in a boiling tube and ask the students what has happened to the mass. This leads on to gases having mass and the mass decreases because the gas escapes from the open boiling tube.Equipment: 2 x 100 cm3 glass beaker, 2 boiling tubes, boiling tube rack, electronic balance, eye protection, lead nitrate solution (about 40 cm3 of 0.5 mol dm-3), potassium iodide solution (about 40 cm3 of 0.5 mol dm-3), hydrochloric acid (about 20 cm3 0.5 mol dm-3), 2 g marble chips

carbonate.The expected percentage mass of copper oxide is 64.4% of the mass of copper carbonate used. Students can be asked why their values are different to this and how they can improve the experiment. If their value is lower (most likely), they probably did not heat the tube for long enough. They could improve the experiment by heating the tube again, cooling and re-weighing and repeating this until two mass measurements are the same. This technique is called heating to constant mass.

Equipment: For each group: Bunsen burner, heat resistant mat, mineral wool, test tube, test tube holders, a few grams of copper carbonate. Students need access to an electronic balance.

examples one step at a time.

Digital Calculating masses of reactants and products presentation


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2) Revise formulae and balanced equations. Check that students know how to work out the number of atoms of each element in a formula.

CC8c Moles C1.52

C1.53

C1.50

C1.51

Explain why, in a reaction, the mass of product formed is controlled by the mass of the reactant which is not in excessDeduce the stoichiometry of a reaction from the masses of the reactants and productsRecall that one mole of particles of a substance is defined as:a the Avogadro constant number of particles (6.02 x 1023 atoms, molecules, formulae or ions) of that substanceb substance mass of ‘relative particle mass’ gCalculate the number of:a moles of particles of a substance in a given mass of that substance and vice versab particles of a substance

1) When there are large numbers of small items, people usually find the number of them by measuring their mass rather than counting e.g. cashiers in banks check the number of coins in a bag by finding their mass. Have small, sealed jars containing 1 mole of particles of different substances e.g. 18g of water, 12g of carbon, 32g of sulfur, 56g of iron. Explain that these each contain the same number of particles. Ask the students to identify the type of particles in each substance.

Students study the reaction between iron and copper sulfate solution

The students should find that the correct balanced equation is

Fe + CuSO4 → Cu + FeSO4

Equipment: for each group 100 cm3 beaker, evaporating basin, eye protection, filter funnel with filter paper to fit, glass rod, 25 cm3 measuring cylinder, spatula, copper sulfate solution ( 30 cm3 of approximately 0.5 mol dm-3 solution), distilled water, iron filings (1 g, not rusted), propanone. Students need access to an electronic balance. Optional: access to a warm

Demonstrate the formation of precipitates of lead iodide by adding different volumes of lead nitrate solution to the same volume of potassium iodide solution and use these to determine the mole ratio of lead nitrate to potassium iodide and hence the balanced equation.Tell the students that equal volumes of the solutions contain equal numbers of moles of the solutes. The reaction is complete when the lead nitrate has reacted with all the


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in a given number of moles of that substance and vice versac particles of a substance in a given mass of that substance and vice versa

2) Have small, sealed jars containing 1 mole of particles of different substances e.g. 18g of water, 12g of carbon, 32g of sulfur, 56g of iron. Ask the students what they have in common. Explain that taking the relative atomic mass or relative formula mass in grams gives us the mass of 1 mole of that substance and they each contain the same number of particles called the Avogadro constant. Write on the board 602 000 000 000 000 000 000 000, then convert it to standard form: 6.02 x 1023.

oven potassium iodide so there will be no further increase in the amount of precipitate formed. Find the tube where the maximum amount of precipitate first forms. This tube had 4.0 cm3 potassium iodide solution and 2.0 cm3 lead nitrate solution so the number of moles of potassium iodide is twice the number of moles of lead nitrate and the balanced equation is Pb(NO3)2(aq) + 2KI(aq) → PbI2(s) + 2KNO3(aq)

Equipment: 2 burettes or graduated pipettes, 8 test tubes in a rack, bungs to fit the test tubes, ruler, lead nitrate solution (25 cm3 0.5 mol dm-3 solution), potassium iodide solution (40


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cm3 0.5 mol dm-3 solution)

Digital Moles presentation

CC9a Acids, alkalis and indicators

C3.1

C3.2

C3.3

C3.4

Recall that acids in solution are sources of hydrogen ions and alkalis in solution are sources of hydroxide ionsRecall that a neutral solution has a pH of 7 and that acidic solutions have lower pH values and alkaline solutions higher pH valuesRecall the effect of acids and alkalis on indicators, including litmus, methyl orange and phenolphthaleinRecall that the higher the concentration of hydrogen ions in an acidic solution, the lower the pH; and the higher the concentration of hydroxide ions in an alkaline solution, the higher the pH

Ask students to write down three or four facts they can remember about about: acids, alkalis and neutral solutions. They then compare their lists in groups.

Students test a series of indicators including: litmus, methyl orange and phenolphthalein. by adding an alkali to and acid 1 cm3 at a time while measuring the pH and noting when any colour changes occurs.

Students are aware of colour changes for range of indicators and note that the colour change is not always at pH 7

Equipment: TBC

Demonstrate the electrolysis of a number of acid solutions: sulfuric acid, nitric acid and hydrochloric acid collect the gas at the negative electrode and test for hydrogen.

Link to the idea that acids always contain hydrogen ions

Digital TBC

CC9b Looking at acids

C3.5 Recall that as hydrogen ion concentration in a solution increases by a factor of 10, the pH of the

1) Demonstrate diluting copper sulfate solution, roughly diluting it by 50% over

Students find out if the pH value is linked to the concentration of the solution.

Teacher demonstrates the difference in pH between four


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C3.7

C3.8

solution decreases by 1Explain the terms dilute and concentrated, with respect to amount of substances in solutionExplain the terms weak and strong acids, with respect to the degree of dissociation into ions

and over again until the colour cannot seen. Discuss the difference between dilute and concentrated solutions in terms of the amount of solute in a unit volume. Discuss ways of measuring concentrations of solutions eg grams per litre or g dm-3

Equipment: TBC

2) Show students two everyday solutions that contain acids. eg. battery acid and fruit juices.Discuss why you can dink one but not the even though they are about the same concentration? Test the pH of each and initiate class discussion of why these acid solutions might have different PH values and why

Starting with 0.1 mol dm-3 hydrochloric acid students use accurate measuring apparatus to dilute the solution successively by a factor of 10

The students then use pH meters to measure the pH of the solution (least to highest concentration)

This should show the link between pH and concentration. Include questions on concentration and pH.

Equipment: TBC

different solutions of acids with the same concentration eg. hydrochloric acid (pH=1) sulfuric acid (pH=2) , ethanoic acid (pH=4) and carbonic acid (pH=5). Then through class discussion students are introduced to the difference between strong and weak acids and why they will have different pHs. Then show students a fifth solution and measure its pH (should be about 5). Ask students if this is a strong or weak acid? Tell them it is in fact a strong acid, discuss to work out it must be a dilute solution of a strong acid. Discuss the differences between dilute and concentrated and strong and weak when talking about


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one might be more acidic than another.

solutions.

Equipment: TBC

Digital TBC

CC9c Bases and salts

C3.9

C3.11

C3.13

C3.15

C3.17

Recall that a base is any substance that reacts with an acid to form salt and water onlyExplain the general reactions of aqueous solutions of acids with:a metalsb metal oxidesc metal hydroxidesd metal carbonatesto produce saltsDescribe a neutralisation reaction as a reaction between an acid and a baseExplain why, if soluble salts are prepared from an acid and an insoluble reactant:a excess of the reactant is addedb the excess reactant is removedc the solution remaining is only salt and water

Investigate the preparation of pure, dry, hydrated copper sulfate crystals starting from

1) show what happens to the pH of an acid solution when a range of common neutralisers are added, eg. Toothpaste, indigestion tablets, lime, etc. Students discuss what happens in these reactions and revise the meaning of neutralisation noting what must be happening to the hydrogen ions in the acid

2) Show class some common salt and dissolve it in water. Ask students how they know the salt is still there? Could it have just vanished? Discuss nature of a solution.Ask students how they could prove the salt was still there. How could they get the salt back? Demonstrate by evaporating water to

Students prepare a sample of pure, dry, hydrated copper sulfate crystals.

Equipment: TBC

Discuss chemical reactions, reactants and products. Show students how to write word and symbol equations, revise formula

Digital TBC


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copper oxide leave the salt.

CC9d Alkalis and balancing equations

C3.10

C3.11

C3.6

Recall that alkalis are soluble bases

…c) Explain the general reactions of aqueous solutions of acids with metal hydroxides to produce salts.

Investigate the change in pH on adding powdered calcium hydroxide or calcium oxide to a fixed volume of dilute hydrochloric acid

1) Ask the students to predict the salts formed in the reaction between some named metal oxides and common acids.

2) Demonstrate the addition of aluminium oxide and calcium oxide powders to water. Aluminium oxide is insoluble so the mixture will remain green. Calcium oxide reacts with water to produce calcium hydroxide, which dissolves to form an alkaline solution so the mixture turns purple.

Equipment: eye protection; test tube rack; 2 boiling tubes; water; universal indicator solution; aluminium oxide powder; calcium oxide powder: small spatula

Students add successive weighed portions of calcium hydroxide powder to a fixed amount of dilute hydrochloric acid, and estimate the pH of the reaction mixture using universal indicator paper. They then plot a graph of pH against mass of calcium hydroxide added.The pH will increase as more calcium hydroxide is added, with the end-point at approximately 1.85 g of calcium oxide. Calcium hydroxide is sparingly soluble (about 0.17 g/100 cm3 H2O) so beyond this excess calcium hydroxide will be seen.

Equipment: eye protection; 100 cm3 beaker; 50 cm3 measuring cylinder; ±0.1 g balance; spatula; stirring rod; white tileuniversal indicator paper; pH colour chart; dilute hydrochloric acid; calcium hydroxide powdergraph paper

Show the students a simple balanced equation, e.g. NaOH + HCl NaCl + H2O. Discuss why this is balanced, then show a more complex balanced equation, e.g. Mg(OH)2 + 2HCl MgCl2 + 2H2O. Discuss why this is balanced, including the use of OH and H to produce water when balancing; and keeping NO3, SO4 and PO4 as units when balancing (rather than counting their atoms separately). Show unbalanced alkali/acid equations and work through balancing with the students.

Digital Equations to balance presentation

CC9e Alkalis and C3.14 Explain an acid-alkali 1) In pairs using paper or Students carry out a practical in Demonstrate the


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neutralisation

C3.16

C3.18

neutralisation as a reaction in which hydrogen ions (H+) from the acid react with hydroxide ions (OH–) from the alkali.Explain why, if soluble salts are prepared from an acid and a soluble reactant:a titration must be usedb the acid and the soluble reactant are then mixed in the correct proportionsc the solution remaining, after reaction, is only salt and waterDescribe how to carry out an acid-alkali titration, using burette, pipette and a suitable indicator, to prepare a pure, dry salt.

mini-whiteboards, students balance equations supplied on the board, then peer assess their answers with another pair.

2) Ask the students to list all the apparatus they can think of that measures volume, then rate each one according to its accuracy and capacity.

which they produce sodium chloride crystals. Titration is used to neutralise dilute sodium hydroxide solution with dilute hydrochloric acid, and then repeated without the indicator. Students then use crystallisation to produce sodium chloride from the solution formed.

The end-point should occur at about 25.0 cm3 (phenolphthalein indicator changes from pink to colourless), with about 0.7 g of sodium chloride produced in total.Equipment: eye protection; 100 cm3 beaker; 250 cm3 beaker; 100 cm3 conical flask; 250 cm3 conical flask25 cm3 volumetric pipette and filler.

technique of titration and the use of the volumetric pipette and filler. Equipment: eye protection; 100 cm3 beaker; 250 cm3 beaker; 250 cm3 conical flask; 25 cm3 volumetric pipette and filler; burette; filter funnel; white tile; 0.5 mol dm–3 hydrochloric acid; 0.5 mol dm–3 sodium hydroxide solution; phenolphthalein indicator.Digital Apparatus for titration presentation

CC9f Reactions of acids with metals and carbonates

C3.11

C3.12

Explain the general reactions of aqueous solutions of acids with (a) metals and (d) metal carbonates to produce salts.Describe the chemical test for (a) hydrogen; (b) carbon dioxide (using limewater)

1) Place a strip of magnesium ribbon in a few cm3 of dilute sulfuric acid in a test tube. Students should observe the effervescence (fizzing). Ask what is in

Students investigate reactions of acids with metals and carbonates to test for carbon and hydrogen.Students will find that magnesium, zinc and iron

Summarise the two different methods of preparing soluble salts - from an insoluble reactant and an acid (using metal, base or carbonate) and from a


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the bubbles.

Equipment: eye protection, test tube in a test-tube rack, piece of magnesium ribbon (about 3 cm), dilute sulfuric acid about 5 cm3 of 0.4 mol dm-3)

2) Remind students about ions and ionic bonding. An ion is a charged particle. Cations are formed by the loss of electron(s) and have a positive charge. Anions are formed by the gain of electron(s) and have a negative charge. The ions are held together by electrostatic forces of attraction between the oppositely charged ions. In the solid state, the ions can only vibrate on the spot, but when they dissolve in water, the ions are free to move around. Revise writing ionic formulae from the symbols of common ions, including some with

effervesce with both dilute acids, although iron may not produce enough hydrogen to pop the lighted splint. Copper does not react with dilute acids. All the metal carbonates react with both dilute acids to provide bubbles of a gas that turns limewater turns milky.Equipment: for each group: eye protection, Bunsen burner and heat resistant mat, dropper pipettes, spatula, test tubes, test-tube rack, wooden splints, limewater, small pieces of copper e.g. foil or turnings, magnesium ribbon (1 cm length), granulated zinc (this works better if it is ‘dirty’), copper carbonate (few grams), magnesium carbonate (few grams), dilute hydrochloric acid (few cm3, 1 mol dm-3), dilute sulfuric acid (few cm3, 0.5 mol dm-3), Optional – bung to fit test tube with a delivery tube attached

soluble reactant and an acid. Include the general steps in the methods and the general equations.

Digital Ionic equations presentation


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brackets.

CC9g Solubility C4.19

C4.20

C4.21

Recall the general rules which describe the solubility of common types of substances in water:a all common sodium, potassium and ammonium salts are solubleb all nitrates are solublec common chloride are soluble except for those of silver and leadd common sulfates are soluble except those of lead, barium and calciume common hydroxides and carbonates are insoluble except those of sodium, potassium and ammoniumPredict, using solubility rules, whether or not a precipitate will be formed when named solutions are mixed together, naming the precipitate, if anyDescribe the method used to prepare a pure, dry sample of an insoluble salt

1) Pour some potassium chromate(VI) solution into a small glass beaker. Slowly add some silver nitrate solution. Students will see an immediate red precipitate of silver chromate(VI) form. Explain that when two solutions containing soluble salts that react are mixed, the ions swap over, so silver chromate and potassium nitrate are formed. All nitrates are soluble, but silver chromate(VI) is insoluble in water so is formed as a precipitate.Equipment: Eye protection, small glass beaker, silver nitrate solution (about 25 cm3, 0.05 mol dm-3), potassium chromate solution (about 25 cm3 of 0.5 g dm-3/less than 0.003 mol dm-3)

Students prepare insoluble salts. Students prepare a white precipitate of silver chloride. This precipitate gradually changes colour to purple when left in light, so dry it in a dark place. The copper carbonate is a blue/green precipitate.

Equipment: for each group: eye protection, 100 cm3 beaker, 100 cm3 conical flask (or other container to collect filtrate), filter funnel, filter paper, glass rod, 25 cm3 measuring cylinder, dropper pipette, distilled or de-ionised water, silver nitrate solution (15 cm3, about 0.05 mol dm-3), sodium chloride solution (25 cm3, about 0.5 mol dm-3), soluble copper salt solutions e.g. copper sulfate and copper nitrate (25 cm3, about 0.5 mol dm-3), soluble carbonates e.g. sodium carbonate and potassium carbonate (25 cm3, about 0.5 mol dm-3)

Demonstrate the formation of the same insoluble salt from different solutions e.g. barium sulfate by adding magnesium sulfate, sodium sulfate and copper sulfate solutions to separate portions of barium chloride solution. Explain that it is always the same precipitate that forms as the barium ions are reacting with the sulfate ions. The other ions are spectator ions. Digital Predicting precipitation interactive


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2) Write these anagrams on the board: busily toil (solubility), blue sol (soluble), no bullies (insoluble), Noels TV (solvent), tousle (solute), loon suit (solution), a tip receipt (precipitate). Ask the students to rearrange the letters to form words related to solubility then to explain the meaning of each word.

Optional: warm oven


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Physics Spec points covered Starter options Practical activity Teacher-led activity

CP4a Describing waves

P2.1

P2.2

P2.3

Recall that waves transfer energy and information without transferring matter.

Recall and use the terms frequency, wavelength, amplitude, period and wave velocity as applied to waves.

Explain the difference between longitudinal and transverse waves by referring to sound, electromagnetic, seismic and water waves

1) Ask students to work individually to list all the types of waves they can think of. Ask how the various suggestions are similar or different, highlighting the ideas to be met in this topic, particularly the difference between transverse and longitudinal waves.

2) Use a 'slinky' spring to demonstrate longitudinal and transverse waves. Elicit the idea that although individual coils in the spring move backwards and forward or side to side, the spring as a whole does not move. Follow up by demonstrating waves with different amplitudes and wavelengths. The amplitude of a longitudinal wave will be easier to see if a small piece of paper is stuck to one of the coils.

In the first part of this activity students use buzzers or lamps to send messages in Morse code. The second part of the activity introduces the idea that variations in the frequency and/or amplitude of a wave can also be used to transfer information.

Show students how a microphone connected to an oscilloscope can be used to represent the characteristics of a sound wave. Challenge them to come up with a short code that uses amplitude and/or frequency variations to send simple messages. Students can test their codes by making the sounds themselves or by using a signal generator attached to a loudspeaker. The students decoding the message can interpret the sounds, or use the oscilloscope trace to see variations in amplitude or frequency. Equipment: cells or power packs; connecting wires; length of bell wire with stripped ends; buzzer; lamp; push switch; copy of Morse code from internet;

Set up a ripple tank with illumination. Place lamp beneath the ripple tank to project the image onto the ceiling. Make sure the tank is level. Use a straight dipper to illustrate plane waves. Ask students to use stopwatches to record the number of waves passing a point in, say, 10 seconds. Dividing the number counted by 10 will give the frequency in hertz. They could also time how long it takes 10 waves to pass a point. Dividing this time by 10 will give the period of the waves in seconds.Equipment: Ripple tank and accessories, stopwatches, rulerDigital Waves video


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microphone, oscilloscope. Optional: signal generator, loudspeaker

CP4b Wave velocity

P2.4

P2.5

P2.15

Recall and use both the equations below for all waves:

wave velocity (metre/second, m/s) = frequency (hertz, Hz) × wavelength (metre, m)

v = f × λ wave velocity

(metre/second, m/s) = distance (metre, m) / time (second, s)

v = x/tDescribe how to measure the velocity of sound in air and ripples on water surfaces.Investigate the suitability of equipment to measure the speed/frequency/wavelength of a wave in a solid (such as an investigation that uses a picoscope) and a fluid (such as an investigation that uses a ripple tank for liquids and a microphone, loudspeaker and signal generator with a data logger)

1) Ask students to describe a thunderstorm, eliciting the fact that you hear thunder some seconds after you see the lightning. Ask them to recall how fast light travels compared to sound, and ask them to suggest how they can use a stopwatch to estimate how far away the lightning was.

2) Tell students that a train is 216 metres long and takes 5 seconds to pass a point on the track. Ask them how they can use this information to calculate the velocity of the train. Recall that the velocity can be calculated by dividing distance travelled by time taken. Tell students that railway carriages are 24 metres long, and 9 of them go

Speed of sound in a solid: The method uses a signal generator (set to square waves at a low frequency such as 20 Hz and maximum amplitude) and piezoelectric transducer to set up a sound wave at one end of a rod, and another transducer to detect the sound at the other end. If possible, allow students to use a long lab bench as their test material in addition to using rods. The oscilloscope should be connected to both transducers such that the signal from the signal generator to the first transducer acts as a trigger. The apparatus is best set up before the lesson, including all the settings on the signal generator and oscilloscope. Explain to students how to use the timebase setting on the oscilloscope to work out the time interval shown by the trace.Speed of waves on water: Each group needs a ripple tank.

Search the internet using 'volcano shock wave' to find a video taken by tourists off Papua New Guinea when the Tavurvur volcano erupted. The shock wave (i.e. a sound wave) can be seen as it causes condensation on the sides of the volcano and in the sky, and the wave is heard around 10 seconds later. Ask students to time how long the shock wave takes to arrive, and to use this and the speed of sound in air (330 m/s) to work out the distance of the boat from the volcano. Note we assume that the light travels instantaneously.

Digital Wave velocity


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past in 5 seconds. Ask them what the frequency of carriages passing is (1.8 carriages per second), and ask them to suggest how to use this and the carriage length to work out the speed of the train. Sketch a train on the board, and draw a transverse wave beneath it, with one wave for each carriage. Elicit the idea that the velocity of a wave can be calculated from its wavelength and frequency.

Students are asked to estimate the speed of a wave by measuring how far it travels in a certain time, and also to calculate it from measurements of frequency and wavelength. Note that the speed of a wave in water depends on the wavelength and the depth, so the results students obtain will depend on both the depth of water in their tank and the frequency they set.

Equipment: Speed of sound in solid: picoscope and computer, or dual-trace oscilloscope; signal generator; 2 piezoelectric transducers; connecting wires; long wooden or metal rod, metre rule. Speed of waves on water: ripple tank (ideally with beaches to prevent reflections), stopwatch, ruler, digital camera

video

CP4c Refraction P2.8 Explain how waves will be refracted at a boundary in terms of the change of speed and direction

1) Demonstrate some of the more common optical illusions that result from refraction, such as a pencil appearing bent when standing in a beaker of water, or a coin

Students investigate the way in which a ray of light is bent when it enters and leaves Perspex or glass blocks.Equipment: glass or plastic blocks of various shapes, including rectangular and

Use a ripple tank to demonstrate refraction occurring when waves move into a different depth of water. Set up a ripple tank with illumination. Place lamp


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in a mug only becoming visible when water is added to the mug. Discuss with the class the basic idea that we see objects because light travels from them to our eyes, and then ask how the pencil could appear bent. Elicit the idea that the light travelling from water to air changes direction.

2) Ask students to work in groups to come up with five key facts about the way light travels and how its direction can be changed. Give them a few minutes, then ask for contributions to a class discussion, recording key points on the board

triangular; plain paper (A3 if possible); power supply; ray box with single slit (and convex cylindrical lens to make the ray thinner)

beneath the ripple tank to project the image onto the ceiling. Make sure the tank is level.The depth of water in part of the ripple tank is reduced by placing a glass block in the tank. The water above the glass should be very shallow and use a low frequency wave.Demonstrate using waves approaching the glass at different angles. Link between changes in wave speed and refraction. Explain that the ripple tank is also acting as model of sound, seismic and light waves refracting.Equipment: Ripple tank and accessories, stopwatches, ruler.Digital Refraction animation


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Written by Mark Levesley, Penny Johnson, Sue Kearsey, Iain Brand, Nigel Saunders, John Ling and Sue Robilliard.


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