# Another teacher’s experience

Ann teaches Science in the early secondary years. She identified the following learning outcomes for a series of three lessons on plastics for a Year 8 class.

Students should be able to:

- distinguish questions that can be answered objectively by scientific investigations from those that involve decisions affected by cultural values and political issues;
- write an outline plan for an experiment to answer one of the questions that can be answered through scientific investigation.

Ann also aimed to develop the following aspects of the student competencies during the three lessons:

## Communication and literacy

Students learn to:

- speak clearly and confidently, and listen carefully and respectfully to others;
- use a range of media to communicate their ideas.

## Critical and creative thinking

Students learn to:

- plan and carry out investigations;
- sort and analyse information and come to conclusions.

## Citizenship

As good citizens, students understand to care for the environment.

Ann introduced the first lesson by showing an old photograph of a room before the advent of plastics and another showing some of the plastic items used in a modern home. She then asked the class to give examples of plastics they used in everyday life. As she listed their answers on the board, she used probing questions to elicit further uses, such as the use of synthetic fibres to make clothes.

Ann then asked the class to talk briefly in pairs to decide whether they thought the invention of plastics was a good thing. After a few minutes, she asked for comments from some of the pairs. While several students talked about how useful and convenient plastics are, a number of students mentioned the problems associated with disposal.

Ann then made a provocative statement. She said: “Maybe scientists should not have revealed their discovery until they had solved the problem of disposal.” While the students realised that she was not wholly serious, this generated discussion about the role of scientists and whether scientists could be expected to take such decisions on their own.

Ann then wrote the first learning outcome on the board and, dividing the class into groups of four or five students, distributed the cards shown below.

1. Plastic furniture lasts a lot longer and is more hard-wearing than furniture made from natural materials such as wood or fabric. | 2. Nylon ropes rot more slowly in seawater than ropes made from hemp (a natural fibre). | 3. Nylon fibres are cheaper to produce than the natural alternative of silk fibres.
4. More tax should be collected to pay for more recycling facilities to help reduce waste. | 5. If we burned plastics to provide energy when we have finished using them, we would not be producing as much pollution, as the amount of rubbish would decrease. | 6. Kevlar (a plastic) is a better protective material than metal armour, as it is stronger.
7. Natural materials like wood and fabric are sustainable. We would do less harm to the environment if we stopped using plastics and used natural materials instead. | 8. Polyester sweaters are easier to keep clean than woollen sweaters. | 9. Some new plastics are biodegradeable. We should replace all plastics with the new biodegradeable ones.

She asked them to discuss the cards and to put each into one of the following categories:

- These questions can be answered by a single scientific investigation.
- These questions can be answered by a series of scientific investigations.
- These questions cannot be answered by a scientific investigation. They involve decisions that take into account social and political issues.

As the students discussed the cards, Ann went around the room listening to the discussion, and checking they understood the purpose of the task and the meaning of the statements. After about ten minutes, she asked each group to explain the decision they had made about one of the cards.
While there was some disagreement, most groups had placed cards 2, 6 and 8 in the first category. Although students had some difficulty explaining clearly and concisely why this was, Ann was able to use their answers to help them understand that these questions identified two materials that were to be tested and a single property that could be measured and compared.

Some groups also felt that cards 1 and 3 could be tested by a single experiment, but others pointed out that card 1 was quite vague. It wasn’t specific about the materials that would be compared, the type of furniture or the treatment it would receive. Similarly, with card 3, while some costs such as the cost of fuel might be found scientifically, transport and labour costs would affect the answer. One student, Saidu, said that that sounded more like Geography than Science!

Most groups had placed cards 5 and 7 in the second category. The group that talked about card 5 said that the question was complex and required data and observations taken from different places over a long period of time. Ann was very pleased with their answer and emphasised the point that complex scientific questions often needed a range of approaches and could not be answered by a single, simple experiment.

Most groups realised that although scientific knowledge could contribute to a decision on the statements on cards 4 and 9, the final decision was — to a large extent — a matter of opinion.
Ann spent the rest of the lesson showing a model plan for an investigation into whether nylon or rubber stretched the most before breaking. She showed this series of PowerPoint slides:

- Slide 1: Title of investigation and hypothesis
- Slide 2: Independent and dependent variables
- Slide 3: List of apparatus and materials
- Slides 4 and 5: Outline of procedure, including how other variables will be controlled.

Ann then asked the groups to choose one statement from cards 2, 6 or 8. She told them that they would be working in this group for two lessons to produce a presentation, following her model, showing a plan to investigate the question that arises from the card they had chosen.

Ann encouraged the students to work co-operatively and gave help to groups who found it difficult to get started. At the end of the second lesson, it was clear that they needed more time and she said they would have 15 minutes to complete the presentation in the third lesson.

Ann realised that there would not be time for all seven groups to give their presentation to the whole class. So, after 15 minutes of the third lesson, she selected one group to present to the whole class in five minutes. When they had finished, she allowed a short time for questions. She then paired the remaining six groups, allocating the members of the group that had already presented to different groups. She then gave each group five minutes to present to the group they had been paired with.

At the end of the three lessons, Ann evaluated what the students had done. She realised that she had spent three lessons on quite a small section of the scientific knowledge in the syllabus. However, she felt it was worthwhile in terms of increasing the students’ understanding of how scientists work and providing them with opportunities to develop the student competencies.

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