09 OCTOBER 2019
AS and A Level Chemistry practicals – student and teacher tips
Challenges for teachers
The obvious challenges for teachers are “Do we have enough time?” and “Have we got enough apparatus and the right facilities?”
The challenge of time can be overcome by planning ahead and allocating spaces in the schedule for practical procedures. The teacher needs to identify crucial practicals. By crucial, we mean those that will really add to learners’ understanding of the theory. Practical work is pointless if there is no follow-up plenary and this must also be taken into account when allocating time.
The question of adequate facilities is not something that can be addressed easily because every school is different. If there are issues concerning equipment, then the crucial practicals need to be identified and provisions for them made a priority.
5 tips for students
1) Remember that practical work is important;it is a component of your examinations. Therefore, make the most of whatever practical experience that you are given and don’t think of it as relaxation time away from theory work.
2) Remember that practical work is related to the rest of the syllabus. If you are not sure why you are doing the practical – ask your teacher to explain. When you are told that you will be doing a practical investigation, write down what you think are the aims of the practical work and what you hope to get from it.
3) If you have a practical partner, then agree responsibilities. For example, if you are measuring the rate of a reaction by following the change in the volume of gas produced, one of you can measure the time and help countdown to the next reading, while your partner can read the volume.
4) If you are going to do an assessed practical, then ask your teacher what criteria she or he is going to use when allocating the marks.
5) Try and maintain a good balance between your awareness of safety and a confident use of the apparatus. You should by now know how to use a Bunsen burner safely and the difference between gentle heating and strong heating, even some advanced level students think that gentle heating involves a yellow Bunsen burner flame. The practical workbook has a chapter on basic techniques. If this textbook is available, then take a look at this chapter.
5 tips for teachers
1) As we have already said, practical work is time well spent. However, time is not limitless and therefore you have to ration the time available. We know that a limited amount of time is one of the main problems when teaching an advanced level chemistry course. Prior planning is essential. Construct a scheme of work that shows how much time you are going to allocate to theory work, tests and revision for exams. Once this is done, how much time is left over for practical work? What practicals are ones that you deem absolutely necessary.
2) A lack of practical apparatus is another problem. However, there are strategies that can overcome this problem. For example, after teaching the theory underpinning a relevant chapter from the coursebook, a practical circus can be arranged, which covers the main aspects of the chapter. Because it is a circus, you may only need one piece of apparatus for each aspect.
3) Allow time for discussion of practical work. This can be a simple class discussion or alternatively, the practical groups can be allowed to present their findings and be assessed by the rest of the class. Discussions don’t necessarily have to follow the practical they can precede them. This allows students to really understand what they are going to do and what they think the problems are.
4) Practical work that requires a specific set of skills such as titrations, require one lesson beforehand where the students are allowed to practice. Don’t assume that students know what is meant by ‘rough’ and ‘accurate’ titrations. It will be helpful for the students to know how marks will be allocated according to their technique.
5) Spend time on the accuracy of apparatus and systematic errors. See the practical workbook for a survey of how to calculate the percentage errors for different sets of apparatus. This is more often than not the weakest component of practical investigations. Make sure your students know how to draw up a results table and have a good knowledge of the vocabulary used.
By Mike Wooster
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