entered these readings on a table. Based on the results of the investigation, they drew a conclusion which addressed the hypothesis. The investigation can therefore be classified as guided. The teacher played a supportive role in facilitating the learners' progress through the investigative process. Through the use of skilful questioning, he encouraged the learners to reflect upon what they had done, and to rethink decisions they had made. Mr Pillay also explained that there were certain skills in this investigation which needed to be modelled. He mentioned how he had spent some time showing the learners how to decide which scale to use on the ammeter and voltmeter, and how to take readings.
After showing them how to take these readings they were given a worksheet with the ammeter and voltmeter gauges drawn. On these gauges different readings were shown.
They had to do give these values of the readings (Mr Pillay, interview).
This excerpt reflects that although the learners had the autonomy in collecting data, the teacher provided sufficient guidance.
4.4 MRS REUBEN'S CLASS: A GUIDED INVESTIGATION ON
applications for a place in Grade 8 at this school. The average class size in grade 8 and 9 was forty two, and in Grades 10, 11 and 12 it was thirty eight. The guided investigation was observed in a class with forty learners. There were seven Grade 9 classes and the learners were graded according to their performance in Grade 8. The class observed was a
"C" class. The teacher, Mrs Reuben had twelve years' experience teaching Natural Science. She had a teaching diploma with majors in Physical Science and Mathematics.
The teacher informed the researcher that the management of the school subscribed very strongly to the OBE approach. The principal often invited subject advisors to address subject departments about OBE and the curriculum changes in the FET phase. All teachers were therefore strongly urged to adopt a learner-centred approach in the classroom.
Mrs Reuben informed me prior to the lesson that the class would be conducting an investigation to show that one of the products of combustion of a candle was carbon dioxide. It was brought to my attention that combustion reactions had been covered in the previous lesson, and learners possessed the knowledge that during combustion a substance reacts with oxygen. The learners were also taught that carbon dioxide turned clear
limewater milky. The teacher told the researcher that due to the overcrowding in the laboratory, the learners would be working in a covered area outside the laboratory. The teacher explained further that such areas had been created throughout the school to alleviate the overcrowding situation.
4.4.2 A description of what happened in Mrs Reuben's class
As the learners arrived for the lesson, the teacher asked them to stand in two lines of boys and girls. The teacher then placed learners into groups by calling out the names of
members in each group. There were four groups of seven learners and two groups of six learners. The groups were then directed to the tables which were set outside. The teacher later explained to me that she composed the groups so that learners who were overly talkative in class could be separated. The teacher informed the learners that they were to design and then carry out an experiment to show that carbon dioxide was a product of combustion. She also told them they would be assessed for the investigation and impressed upon them the need to take the task seriously. They were expected to complete the
investigation within two lessons. Each lesson was of fifty minutes duration. The learners were told that the present lesson would be used for planning, and the investigation would
be conducted in the next lesson. The next lesson was going to be in three days' time. The groups would be responsible for bringing the apparatus to be used. The groups were told to inform the teacher in advance should they not be able to provide the apparatus. The teacher handed out a worksheet which included the following questions and instructions to guide learners in planning the investigation, conducting the investigation and drawing
conclusions
1. Brainstorm ideas in your group.
2. Decide what apparatus you will use.
3. Describe how you will do the investigation.
4. Draw the apparatus you will use.
5. Describe what happened.
6. Write an equation for the combustion of the candle.
7. What did you conclude ?
The teacher read the worksheet and told the learners that each group would need to hand in a worksheet at the end of the investigation.
The groups began brainstorming. This was the planning stage of the investigation. The learners were told that they should have a plan by the end of the lesson. As the groups engaged in discussion on how to conduct the investigation, the teacher sat at her table and marked tests from a previous lesson. The teacher sat at the table for ten minutes. During this time it was observed that a few learners visited other groups. They appeared to engage in conversation which was unrelated to the task given. The teacher shouted at these
learners to return to their group. When questioned at the end of the investigation about this period when learners were left on their own, Mrs Reuben explained that learners should be given some space to 'talk things through.' After this period of time, the teacher went to each group and asked to see what they had written on their worksheet. At this point, three of the six groups had written the plan and the other groups were still in discussion about what to do in the investigation. At the groups where the learners had already formulated the plan, the teacher used probing questions which enabled the learners to clarify their plan. If their plan was inadequate, the teacher asked them to reconsider these deficiencies.
She also made suggestions where necessary.
The following excerpt illustrates how the teacher probed a group's plan. The group was made up of seven members with Trevern as the group leader.
Mrs Reuben: Guys tell me what you will do.
Trevern: Ma'am, we will burn the candle. This gives CO, We then take something burning like a match. If it goes off it proves the candle gave CO".
Trevern: Okay so will you hold the burning match close to the candle flame ? [The learners all answered "yes ma 'am.'7
Mrs Reuben: Okay, I want you to think about this before you conduct your experiment.
How do things burn and what is needed for burning ?
[The learners reflect on this question and engage in a group discussion.
Thereafter teacher returns to the group.]
Mrs Reuben: Have you thought about this ?
Vijay: Ya, we know that oxygen is needed for burning.
Mrs Reuben: Good. You are saying that the match that's burning will go off in air when held near the candle ?
Vijay: Ya.
Mrs Reuben: Think about this....in air. Yes, Suren ?
Suren: I am not sure....but with the oxygen in the air it will carry on burning.
Mrs Reuben: Good. So what do you thing you need to do ? Suren: Collect the gas in a container.
Mrs Reuben: Yes, now I want you to design this and show me what you will do.
[After a discussion, the group leader calls for the teacher.]
Mrs Reuben: Okay Trevern what's your plan ?
Trevern: We think we need to have a bottle to store the CO,. We can put the candle in the bottle...light it and then quickly put the match there.
The teacher had similar exchanges with other groups. In an interaction with another group, the learners explained to the teacher they would collect the gas evolved through
combustion in a container. They would then place an ant in the container and seal the container. The learners suggested that if the trapped ant died it would prove that the gas produced would have to be carbon dioxide. The teacher questioned the learners about whether it would be the lack of oxygen or the trapped carbon dioxide that would kill the ant. The learners had a rethink about their plan and then proposed another container should be used as a control. A second ant would be placed in this container which would then be sealed. The learners would compare the times it took for the ants to die. The teacher made no comment regarding the killing of the ants. The teacher did not appear concerned about
the learners choosing to use an ant in the investigation, nor did she try to persuade them to change their plan.
By the end of the lesson all groups had formulated a plan to conduct the investigation. The learners were asked to bring their own material for the investigation. The teacher told the learners she would provide chemicals should they be required. In the next lesson, the groups conducted the investigation. The teachers observed what the learners were doing and intervened either when help was solicited or she felt the learners were making no progress. She asked guiding questions or offered advice. The researcher followed the progress of the Trevern's group who in the previous lesson had formulated a plan where they would place the burning candle in a bottle and then put a burning match into the bottle. It was noted that the match did not extinguish immediately.
The following exchange shows how the teacher asked the group to review their plan and consider another procedure to test for the presence of CO2 .
Mrs Reuben: What do you think is the problem ? Trevern: There is not enough CO,
Mrs Reuben: Why not ? Trevern : It is escaping.
Mrs Reuben: I want you to think of another way to show that the gas formed here is CO2. You can look at your notebooks.
[Trevern's group engages in a discussion. After a few minutes, Mrs Reuben returns to the group. The learners have a sketch of the apparatus for their investigation.]
Mrs Reuben: Okay this looks interesting. What do we have here ?
Trevern: We realized that limewater is another way to test for the CO2 . The bottle can be filled with limewater. Then if you put the burning candle it will turn milky.
Mrs Reuben: Try it out.
[After visiting other groups, the teacher, returns to Trevern's group. They are now carrying out the investigation. The learners prepare a solution of limewater in a bottle. A burning candle is made to stand in the bottle. The researcher observes that the limewater does not turn milky as they had expected] Mrs Reuben questioned them on this.
Mrs Reuben: Why do think there is no change to your limewater ? Vijay: Maybe there is no carbon dioxide.
Mrs Reuben: Are you sure ?
[The teacher redirects the question to Trevern]
Mrs Reuben: What do you think Trevern ?
Trevern: I think the problem is not enough gas. Maybe some escapes.
Mrs Reuben: So what can you do ? Trevern: Need to cover it up quickly.
[The group tried this. This time the limewater did turn milky]
The teacher played a similar role when visiting other groups. For example, in the group where the learners were comparing the times for the ant to die in the container filled with carbon dioxide and the control container with the normal air, the teacher intervened and questioned the learners about the different sizes of the container. The learners came to realize that size would be a variable that would need to be controlled in order to make the test fair. At the end of the lesson, all groups handed in their worksheets.
4.4.3 Follow-up on lesson in Mrs Reuben's class
The teacher defined the investigation task for the learners. The learners planned and carried out the investigation. The teacher supported the learners by asking questions which
encouraged the learners to reflect on and justify their plan. When groups were making no progress in conducting the investigation the teacher asked them to review their plan. The teacher also made suggestions which enabled the learners to reformulate their plan.
The investigation in Mrs Reubens class, although guided, represented a different scenario compared to the guided investigations in Mr Botha's and Mr Pillay's class as the class size was much bigger. There were forty one learners in the class. To accommodate the large number of learners, certain actions needed to be taken. Firstly, the class was moved outside for the lesson. The teacher explained this as follows:
The large class hasn't hindered me at all. I think investigation can still be done. It does make it uncomfortable in the lab so they were asked to do it outside. The cleaners were helpful in setting up the tables. The students need room to move around. In the lab it is dangerous to have overcrowding in the event of an accident. You would see that there are mainly seven pupils per group. (Mrs Reuben, interview)
Secondly, the learners were made to work in groups or six and seven whereas in Mr Botha's and Mr Pillay's class where a guided investigation was also being carried out, the learners were placed in smaller groups of four. Thirdly, the learners were asked to bring their own apparatus for the investigation. In offering a reason for this, the teacher
explained that there was insufficient apparatus for all the groups, and also she felt that by learners bringing their own apparatus it would encourage some creativity in them. The
above investigation therefore illustrates a guided investigation carried out in a large class of learners with few resources.
4.5 MRS NAIDOO'S CLASS: A STRUCTURED INVESTIGATION ON