The students were preparing for the Edexcel, single award, GCSE Science, which requires six modules of work to be completed. The module being studied was ‘Chemistry in Action’ and involved work on the formation and processing of crude oil, combustion of hydrocarbon fuels; plastics; uses of enzymes in food production; and neutralisation and thermal decomposition reactions. Four lessons were allotted to the part of the module entitled ‘Types of chemical reactions’, two of which were to be used to cover the specification that “candidates will be assessed on their ability to understand that neutralisation can be used to make salts, some of which may be used as fertilisers.” and the idea that soils can be a variety of acidities and consequently may require neutralisation for plants to grow.
Using the exam syllabus, the ‘Letts’ GCSE Science revision guide and school resources, two lessons were drafted, discussed with my mentor and from these, detailed lesson plans were developed. Due to the low ability of the group, the first lesson was to include a large amount of revision from key stage three regarding the nature of acids and alkalis. It was additionally decided that all tasks should be fairly short and involve as much participation from the class as possible so as to maintain attention, and that, in order to establish what information was already known about neutralisation, a concept map would be drawn at the beginning of the first lesson.
In evaluating the first lesson draft several decisions were made. The first of these was that although the class may have been more familiar with the reaction of HCl with NaOH to form the common salt, sodium chloride, preparation of ammonium sulphate would be more beneficial on account of the ability to link one lesson with the next. Use of ammonium sulphate also allowed explanation that sodium chloride whilst being called ‘salt’ is not the only compound given such a definition in a scientific context. Additionally the group were to be permitted to work in pairs with whom ever they chose. Since the lessons were on consecutive days, without timetabled homework between them, any assessment relating to the first lesson had to be completed within class time, and it was decided that the most efficient way to do this was using a worksheet which would also provide a plenary to the lesson.
After the first lesson, an evaluation yielded several points, from which revision was made to the second lesson plan. The most notable issue that was discussed regarding the first lesson was that too much knowledge regarding acids and alkalis had been assumed. On account of this it was decided that the time taken to recapitulate the ideas from the worksheet was to be extended and the crossword was to be discussed as well as the cloze procedure questions. Additionally the time for the second lesson plenary was to be extended so that even if the practical component was to overrun, or any problems occurred during the lesson, there would be ‘contingency time’ in order to fully reinforce the most important ideas in the sequence.
The other decisions revolved around organisation for practical work. Whilst the majority of the students had been ‘on-task’ during the practical in the first lesson, it was felt that whilst for each girl to test each soil pH would be too time consuming, and was likely to result in an excessive amount of movement around the room, the students should be required to work individually. As a consequence, the decision was taken to spread the apparatus around the classroom and assign two girls, who did not normally work together, to each type of soil and ask for a result from each student such that the idea of taking repeat readings could be briefly discussed. Their results were then to be written on the board alongside their names such that anyone who had not completed the task would be easily identifiable. Since everyone required each result, they were accountable to the rest of the students and therefore this method aimed to provide a certain degree of motivation to produce a result for the rest of the class.
After teaching the second lesson, this too was evaluated. It was decided that the reorganisation of the practical work had been successful with regards to motivation and had resulted in a scenario in which all students appeared to be ‘on-task’. Discussion of use of lime or peat to alter soil acidity was understood in terms of neutralisation, however some students became confused when fertilisers were included in the list of what was put on soils and the fact that these can be made by the same type of reaction. One student asked “so do the fertilisers neutralise the soil too?” This was clarified by sketching a ‘flow-diagram’ on the board showing what compounds are put onto soil and how each is made. It was further explained by setting up three Petri-dishes to try and grow radishes, one of which was fed only water, another was fed the class’ ammonium sulphate salt, and the third with a commercial fertiliser. Unfortunately, as it turns out, one week after the lesson, only the control had started to sprout. Encouragingly however, this unexpected result was able to be explained by several students by the idea that the dosage of fertiliser given may have been too high, and have poisoned the seeds.
The wonderwall exercise at the end of the lesson did not provide a large amount of assessment of the pupils since only three were involved in answering questions, however it seemed to show that the majority of the girls could remember basic facts about acids and alkalis, and knew why fertilisers may be used. To a certain extent it also gave a measure of who had gained most from the lesson, as it was these students who were the most vocal with regards to asking questions. This method of assessing achievement does not however necessarily account for the very quiet pupils. The initial list of words was added to in order to offer more of a challenge for one of the stronger pupils towards the end of the lesson, and by score-keeping in the corner of the board, a competitive element was introduced which seemed to increase enthusiasm for the exercise and, at this point, even the quietest of the students took part in answering her peers questions.
References:
Smith, R. (1988) “What makes a good teacher?” Teaching and Learning in the Secondary School, Ed: Bob Moon and Ann Shelton Mayes, 1994, Routledge in association with the OU
Bennett, N. and Dunne, E. (1994) “Managing Groupwork.” Teaching and Learning in the Secondary School, Ed: Bob Moon and Ann Shelton Mayes, 1994, Routledge in association with the OU
Gott, R. and Mashiter, J. (1994) “Practical work in science – a task based approach?” Teaching Science, Ed: Ralph Levinson, 1994, Routledge in association with the OU)
Edexcel, Specification B, GCSE science syllabus
