a problem-solving approach in teaching Science, Technology and ...

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A problem-solving approach to STS

Kidney failure and dialysis: a problem-solving approach in teaching Science, Technology and Society Yeung Chung Lee How can we engage pupils in learning STS, apart from employing common approaches like data analysis, case studies and class debate?

Science, Technology and Society (STS), a term first suggested by Ziman (1980), has become a catchphrase to describe an approach to studying science and its interactions with technology and society. STS elements have been incorporated into the science curricula to different extents in different places. In the UK, starting from key stage 2 (ages 7–11), pupils are expected to ‘think about the positive and negative effects of scientific and technological developments on the environment and in other contexts’; and in key stage 4 (ages 14–16), pupils ‘explore how technological advances relate to the scientific ideas underpinning them’ and ‘consider the power and limitations of science in addressing industrial, ethical and environmental issues’ (DfEE/QCA, 1999). The National Science Education Standards of the United States incorporate STS elements within the ‘Science and Technology Standards’, which ‘establish connections between natural and designed worlds’, and within the ‘Science in Personal and ABSTRACT This article describes the use of a problemsolving approach in teaching a Science, Technology and Society (STS) issue. A scheme of work is presented which engaged secondary biology pupils in devising treatment methods for patients suffering from chronic kidney failure. Through the problem-solving process, pupils were led to understand and appreciate how science is applied to solve an important health problem. Apart from enhancing motivation and engaging pupils in the learning process, evaluation showed that the approach had the added value of clarifying pupils’ misconceptions of important physiological processes.

Social Perspectives Standards’, which ‘give students a means to understand and act on personal and social issues’ (National Research Council, 1996). In Hong Kong, the new senior secondary biology and physics curricula incorporate ‘STS connections’ as an extension to traditional content areas (Curriculum Development Council, 2002a, 2002b). Many of these curricula advocate an issue-based approach in teaching STS, focusing on the socioeconomic, environmental or ethical impact of issues arising from the application of various branches of science. Common issues are air pollution, GM food, cloning and mobile phones, to cite just a few. Approaches such as data analysis, case studies, discussion and debate are commonly used to achieve the objectives. To extend our repertoire of teaching approaches, this short article uses chronic renal failure as an issue to explore an alternative approach to teach STS. Pupils were engaged in a problemsolving activity that required them to apply scientific knowledge gained from their biology class. Through the problem-solving process, pupils could more readily understand and appreciate how scientific knowledge bears on the resolution of human or societal problems.

Background to the problem Hundreds of thousands of people around the world are suffering from chronic renal failure as a result of different kinds of diseases or disorders. While there is a general shortage of kidneys available for transplant, dialysis is a viable option to sustain their lives until transplant. Dialysis is the means for removing wastes and excessive fluid from the body to maintain its proper functioning. It is supposedly School Science Review, March 2006, 87(320)

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Figure 1 Set-up for performing peritoneal dialysis.

employed as a short-term treatment option so that people’s lives can be sustained while they are waiting for kidney transplant. However, in view of the limited number of donors, dialysis has become the only kind of treatment available to many patients. It is estimated that more than one million people worldwide are dependent on some forms of dialysis (Baxter, 2006). At present, two options of dialysis are available to these patients: haemodialysis and peritoneal dialysis. In haemodialysis, the blood of the patient is pumped through a very long tube made of artificial dialysis membrane contained in the socalled ‘kidney machine’. Waste substances diffuse from the blood to the surrounding dialysing solution, or dialysate, through the membrane, because there is a concentration gradient between the two media. Peritoneal dialysis was developed more recently. In this form of dialysis, the dense capillary network in the peritoneum, which lines the abdominal cavity and the gut, is used as the dialysis membrane. Dialysate is introduced into the abdominal cavity through a tube called catheter. Just as in haemodialysis, toxic substances and water move out of the blood into the dialysate, but this time through the blood capillary wall instead of an artificial dialysis membrane. The dialysate is kept in the body for a few hours before it is drained from the abdomen. New dialysate is then introduced so that dialysis can take place 24 hours a day. Figure 1 shows how the dialysate is drained out

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by siphonage and new solution is introduced into the abdomen by gravity. With some training, the patient can administer the treatment at home, hence allowing them to lead fairly normal lives. Apart from this, patients under peritoneal dialysis have a more stable blood composition than those under haemodialysis, since dialysis takes place more or less continuously within the body. However, the risk of peritonitis is great since bacteria may enter through the artificial opening to the abdominal cavity. Neither of these forms of dialysis can replace the kidneys, as these have other functions such as the secretion of erythropoietin essential for production of red blood cells.

The problem-solving activity The following activity was tried out with two classes of 15–16 year-olds in a Hong Kong secondary school, a total of 79 pupils. They were of average ability and had learnt about the functions of the kidney and the principles of diffusion and osmosis. They had performed dialysis by using Visking tubing to separate starch from glucose. The aim of the activity is to enable pupils to understand the role of dialysis in treating renal failure and to enhance their problemsolving ability. The lesson lasted for approximately one hour and twenty minutes. At the beginning of the lesson, pupils were presented with the problem:

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‘How can waste substances be safely removed from the body of patients suffering from chronic renal failure?’ Then they were asked to design a simple system to solve the problem, utilising the knowledge they had acquired in previous biology lessons.

Materials and apparatus The pupils were provided with the following: Visking tubing, string, distilled water, syringes, beakers, test tubes, test-tube rack, droppers, blotting paper, bromothymol blue, urease, electronic balance, materials for making a ‘blood’ sample (sucrose, glucose, starch, proteins, amino acids, salts, urea, distilled water).

Guidelines on procedure To assist the pupils through the enquiry, the following guidelines were provided: 1 Make up a ‘blood sample’ with the substances provided. (You should select only the substances present in human blood.) 2 Construct a set-up to remove wastes from your ‘blood sample’ using the materials and apparatus provided. Draw your design. 3 Predict what will occur when the system is left running for some time. 4 Briefly describe the tests you will conduct before and after the experiment to check if your system works. [It was suggested to pupils that it would be helpful to measure the weight of the ‘blood’ sample in the Visking tubing using the electronic balance. The test for the presence of urea in a solution sample was provided to pupils since they had not done this before – see Box 1.] 5 Carry out the experiment and perform the tests deemed necessary. 6 Record your results.

Follow-up discussion After the enquiry, pupils were led to discuss the following questions: l Could your system perform the functions of the kidneys? Why? l How could you apply your design to clinical use? What technical problems would you expect to encounter?

Post-activity discussion After the discussion, pupils were introduced to the use of dialysis as a treatment method. The principles of the two forms of dialysis, haemodialysis and peritoneal dialysis, were explained so that pupils


BOX 1

Test for the presence of urea in a solution sample

Ten drops of the sample is placed in a test tube. Five drops of bromothymol blue (yellow in acidic medium) are then added, followed by five drops of 2% urease. If the sample contains urea, it will be broken down into ammonia, which will turn bromothymol blue from yellow to blue. (SAFETY: Urease, like other enzymes, may cause allergic reactions in some people. Bromothymol blue, and the small amount of ammonia produced in the solution mixture, may cause irritation. Hence, care should be taken to avoid contact with eyes, skin and clothes when handling the above chemicals. Pupils should wear safety goggles. Hands should be washed thoroughly after handling. Adequate ventilation is needed to avoid breathing vapours of bromothymol blue and ammonia solution. Any spills should be mopped up with inert material immediately.)

could compare them with the set-ups they had designed. Using information provided on the website of the International Society for Peritoneal Dialysis (see websites), pupils were guided to trace the development of peritoneal dialysis, leading to its establishment as a treatment option to haemodialysis. This was to enable pupils to appreciate the painstaking process scientists and technologists carry out in their continuous quest to provide better solutions to this chronic health problem. Pupils were also led to consider the limitations of dialysis as an option to kidney transplant and why there were so few transplants compared with the number of patients on the waiting list. They were then encouraged to consider various possible ways of increasing the number of potential donors, and the legal, ethical and educational implications of different options.

Evaluation The approach described in the previous section was designed to introduce pupils to the application of scientific principles in technology and how it impacts on society. Through the problem-solving activity, pupils were actively engaged in developing solutions to the problem by applying what was School Science Review, March 2006, 87(320)

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Figure 2 A set-up for dialysis designed by pupils with ‘blood’ inside the Visking tubing and dialysate outside.

learnt in previous lessons. They found this activity interesting yet challenging. In designing their setups (an example is shown in Figure 2), pupils had to draw on knowledge about the composition of blood, functions of the kidney as an excretory and osmoregulatory organ, the principles of diffusion and osmosis, and the concept of semi-permeable membrane. They also needed to draw on the dialysis experiment they had carried out previously, using Visking tubing to separate starch from glucose. Hence, an added value to this activity is to enable the teacher to check pupils’ understandings of these aspects. As a result, a number of misconceptions were identified during the activity. For instance, some pupils erroneously added starch to their ‘blood’ sample, thinking that blood contains starch. Some appeared doubtful as to whether proteins were present in blood, with the understanding that proteins could not be absorbed through the gut. Nearly all pupils used distilled water as the dialysate, believing this was most effective in extracting wastes from the ‘blood’. When pupils were asked to predict whether their blood sample would increase or decrease in weight after the treatment process, nearly all said that it would lose weight because of the movement

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of solutes out of the Visking tubing. This showed that many pupils did not realise that, in their case, there was a net gain of water in the Visking tubing because of osmosis; nor were they fully aware of the osmoregulatory function of the kidney. There were a lot of ‘aha’ responses when they came to realise the problem of using distilled water as the dialysate. At this point, they began to see the need to add essential solutes such as glucose and salts to the dialysate to draw out excessive water from the ‘blood’ and avoid loss of these essential substances during dialysis. At the end of the lesson, I administered a questionnaire to the pupils to elicit their perceptions about the lesson. They were asked to indicate their agreement with a number of statements on a fivepoint Likert scale, ranging from ‘strongly agree’ (5) to ‘strongly disagree’ (1). In general, pupils agreed quite strongly that the lesson increased their understanding of osmosis (mean = 3.81), the composition of blood (mean = 4.11) and the functions of the kidney (mean = 4.04). The lesson also helped them understand how dialysis could help patients filter out unwanted materials (mean = 3.93). Aside from conceptual understanding, the lesson was also effective in achieving certain affective outcomes; for instance, pupils became more aware of the importance of the kidneys to bodily health (mean = 4.12), showed more concern with protecting their own kidneys (mean = 4.14) and valued their health to a greater extent (mean = 4.16). Pupils seemed to become more willing to donate kidneys after death (mean = 3.69). Yet, the moderate mean value of agreement relative to other statements implies that it is difficult to change pupils’ attitudes towards organ donation, which is perhaps deeply rooted in societal culture. Because of time constraints, there was only limited discussion toward the end of the lesson on the evolution of dialysis, though pupils were eager to listen. With hindsight, this part could be treated as extended project work. Pupils could be asked to find out the answers to the following questions: l What prompted scientists to develop peritoneal dialysis as an alternative to haemodialysis? l What were the difficulties encountered by scientists in researching into peritoneal dialysis and how were they overcome? l What were the milestones or turning points in the development of peritoneal dialysis? l Can you distinguish between the roles played by scientists and technologists in developing viable systems for peritoneal dialysis?

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l What are the advantages and disadvantages of peritoneal dialysis as compared with haemodialysis? l What are the limitations of dialysis as a longterm treatment method? What are the functions of the kidneys that cannot be replaced by this kind of treatment? l What are the implications of dialysis for the health-care system and society as a whole? l What future developments do you predict will occur in the continuous evolution of treatment methods for kidney failure?

famines?’ and ‘How can we recycle domestic wastes in agricultural or other man-made ecosystems?’ In the first example, pupils could be asked to suggest food rations for relieving hunger or malnutrition. To do this, they need not only to apply knowledge about nutrition but also to take into account budgetary and logistical constraints in sending food to faminestricken areas. From this, pupils could enquire into more long-term solutions to resolve the problem of starvation, from both scientific and political and socio-economic perspectives. In the second example, pupils could experiment with composting and laboratory models of wetland ecosystems as a means to recycle solid and liquid wastes, and consider the technological and environmental implications of large-scale adoption of these methods. The process pupils go through in this type of activity mirrors that undertaken by scientists and technologists in solving real-life problems. With pupils’ personal involvement in these activities, it is easier for them to develop a sense of ownership of the problem-solving process typical of science and technology. This problem-solving approach, coupled with follow-up discussion on the implications of possible solutions, could serve as an effective vehicle to enhance pupils’ understanding of the interactions between science, technology and society.

Summary Teaching of STS can go beyond analysing data, discussing the socio-economic, environmental or ethical implications of scientific and technological developments, or debating controversial issues. Teachers could engage pupils in solving genuine human problems through the application of scientific knowledge, hence prompting them to think more deeply about the issues. This short article suggests how this could be done in the case of treating kidney failure. There are other problems relevant to secondary science curricula to which a similar approach could be applied, such as ‘What kinds of food could be delivered to areas devastated by wars or

References Baxter (2006) Kidney disease. Available at: http://www.baxter.com/conditions/sub/renal_failure.html (visited: February 2006). Curriculum Development Council (2002a) Biology curriculum guide (Secondary 4–5). Hong Kong SAR: Printing Department. Available at: http://cd1.emb.hkedcity. net/cd/science/en/syllabuses/biology/synopses/s4-5bio_ e.pdf Curriculum Development Council (2002b) Physics curriculum guide (Secondary 4–5). Hong Kong SAR: Printing Department. Available at: http://cd1.emb.hkedcity. net/cd/science/en/syllabuses/physics/synopses/phy_ cg2002e.pdf

DfEE/QCA (1999) Science: The National Curriculum for England. London: The Stationery Office. National Research Council (1996) National Science Education Standards. Washington, DC: National Academic Press. Ziman, J. (1980) Teaching and learning about science and society. New York: Cambridge University Press. Website International Society for Peritoneal Dialysis (for the emergence of peritoneal dialysis): http://www.ispd.org/ history/genesis.php3 (visited: January 2005).

Yeung Chung Lee is a science lecturer at the Hong Kong Institute of Education, Hong Kong SAR, China. Email: [email protected]


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