Análisis de Desbaste para placa Corazón

In the first interview when asked about the types of assessment he intended conducting during this series of lessons, he stated his intention was to ask learners to complete a worksheet, to write a scientific report, to write a “home test”, as well as giving learners lots of practice in balancing chemical equations. None of these activities were for formal assessment purposes and, although not always stated as such, were for formative assessment purposes. However, Batandwa was fully aware of the summative assessment requirements and his intention was to use the informal assessment activities to prepare learners for these summative activities. Although he did not refer to this as assessment, the types of questions he asked will also be discussed. Each of these assessment activities will now be discussed in terms of what was being assessed, what some of the learner responses were, and the way in which the teacher assessed these activities.

The objective of the worksheet (Appendix N) that accompanied the teacher demonstration appears to have been to assess mainly learners’ content knowledge and observation skills. The teacher assisted the learners with completing the first reaction in the worksheet, and expected the learners to be able to complete the rest themselves. During the lesson, very few learners actually filled in the worksheet.

In the follow-up interview, when I asked if he had achieved his learning objectives, Batandwa noted:

Somehow, in fact when I looked, not really 100%, because the only way to see whether you have obtained your objective is when the kids actually can understand everything there. I remember I did with the models and everything for the first problem, which was with lithium with water, to get lithium hydroxide and hydrogen, and then I left the two for them to see. Some of the kids managed to see what the product would have been in the other two. But some of them still could not really see. So it was partially achieved really.

[post-lesson interview 1, p.1]

And in a subsequent interview:

I gave them a worksheet you see. Then I moved around to check. So, that tells me that some who are actually lost, and then I saw some that could actually manage something. [post-lesson interview 2, p. 1] This worksheet was not marked by the teacher but as seen in the excerpt above and captured on video, he went around and checked the work of some of the learners. Eventually the teacher worked through the solutions on the board with some learner input.

Although Batandwa was expecting leaners to write a scientific report based on the demonstration, learners were not told beforehand that they were expected to do so. He assumed that learners had a basic knowledge of the structure of such a report based on work they had done in Grade 8, but he nonetheless guided them by giving them the headings they needed to include, and a brief description of what was expected under each of the headings in the following lesson (Figure 5.1).

A sample of five scientific reports were collected and analysed. One learner handed in only a list of chemical equations (words and symbols) and did not present it in the prescribed format. Three were able to state the aim of the investigation, while the fourth learner did not understand the relevance of the demonstration at all, as seen in the excerpt from report shown in Section 5.4.1

Not one learner was able to name all the apparatus used. The apparatus listed by the four learners were:

1. Hydrogen, lithium, sodium and potassium 2. We used razor, twiser and water

3. We used water, metals, lithium for this investigation 4. Water we put in with lithium

The only comment the teacher made on these scripts with regard to apparatus was that he added ‘3 bottles’ on two of the scripts. The marking and lack of feedback below, as in the example of the learners’ work above, in no way assisted in the learner’s understanding.

Figure 5.4 Extract from learner’s scientific report marked by teacher

Reflecting on his assessment of these reports Batandwa says:

What surprised me is that when I was asking about some of the sub-topics there, like method what is it that is expected, some of them seemed as though it was something new. That is one thing that really surprised me. …

What did not really work is the fact that what is assumed as pre-knowledge is not really pre-knowledge. [post-lesson interview 1, p. 3]

A scientific report could be used to assess learners’ knowledge and skills to follow the scientific method. Although the teacher emphasized that the purpose of the exercise was to develop these skills, he gave no constructive feedback on any of the scripts. In an interview Batandwa explained that he used the coke bottles instead of using laboratory equipment to show learners that they could experiment at home, yet none of the reports included the bottles as the apparatus. This could explain why this was the only comment he added to the lists of apparatus. One wonders if the reason learners did not include bottles under apparatus was that they did not consider it to be laboratory apparatus. After marking some of the reports he spent quite a bit of time talking learners through a ‘model scientific report’ on the experiment conducted.

Except for the question about predicting what would happen during the reaction, oral questions during the lesson were mainly lower order questions, which often elicited choral responses from the learners. The teacher also tended to answer many of his questions himself.

It thus appeared that the teacher’s perceptions or knowledge of learners not only influenced the type of practical work he engaged in, but also influenced his assessment strategies.

OK, the second one. Remember I did that orientation of that work on the scientific report and all that. Things that I would add, if I had a more powerful type of student, it would be issues around hypothesizing the question and all of those things. This is more of a short experiment and not a long investigation, so I thought “No” let me leave that. [post-lesson interview 1, p. 4] However, this excerpt also shows that Batandwa purposefully selected the focus of assessment in different assessment tasks.

He recognised the limitations of some of his learners but due to the pressure to complete the content specified in the curriculum, he felt compelled to “move on” despite the learners’ lack of understanding:

With those ones it is a bit of a problem. I managed to see at least what’s going on. But, some of them really it is beyond their capacity. Maybe some of those might not even take science next year that is why I thought let me move on. Otherwise if I stay there, because of those, I might end up not covering everything in the syllabus. [post-lesson interview 2, p. 3]

In an examination about a month after the practical, a question on the combustion of magnesium experiment was included. The questions focused mainly on writing the balanced chemical equation, and although this had been included in the practical worksheet, learners

achieved an average of only 13% for this question. This question did not refer to the law of conservation of mass, which was the main concept the teacher intended focusing on in the experiment. In an interview with learners a few days, after the series of lessons observed, when asked what the popping sound they heard during the demonstration indicated, the learners’ responses included: ‘ it is dangerous’,’ don’t put fire near dangerous chemicals’, but none of them mentioned that the gas produced was hydrogen. Or when asked what reacted with magnesium in the combustion experiment, none of them knew, and all they remembered was that magnesium burns with a bright white flame.

In conclusion, Batandwa is knowledgeable about formative and summative assessment, recognized his learners’ limitations and was able to develop assessment tasks that assessed both skills and content. The nature of these assessment tasks were sometimes influenced by his perceptions of the learners. However, poor marking and lack of constructive feedback in the assessment of these tasks hampered the learners’ potential to have a positive impact on learning in his class.