Last week my second year class (NC Year 8) were given the task of modelling huddling behaviour in penguins as part of our ‘Adaptations’ topic. We watched a 3 minutes BBC Attenborough clip of penguins huddling and I explained the term ‘model’ to them in the science-sense of the word. I then gave them the task of modelling this behaviour using glass ware instead of penguins. The aim of doing this practical, which I shared with them, was for them to practise identifying variables (IV, DV and CVs) and to practise table design. I also wanted them to practise independent experimental design – I had this group last year and we’d made great progress using our “Brain, Book, Buddy, Boards” system before they were allowed to ask me for help. The results of the experiment were not at all important to me.
Arguments for allowing students to design their own experiment:
- I love seeing students really using their brains rather than following a method in a zombie-like fashion. I want them to think about the problem and to engineer a solution. I love them hearing them discuss with their practical partner how to keep their test fair – in my view this is REAL science.
- Sometimes, such as in this case, the results don’t matter. Some groups only got one result but they had designed a great experiment and we’d had interesting discussions about their set-up.
- This way develops independent learning skills – there is no chance to passively partake in a lesson and students have to think for themselves.
- By allowing students to make mistakes with table design, e.g. variables the wrong way around, mixed units, incomplete headings etc you have a range of great resources to share and discuss with the class. Having just marked their plans I now know ‘O’ is struggling with table design and ‘M’ and ‘J’ need some help with repeatable and reproducible definitions.
- Key Stage 3 is largely free from needing to know fixed methods and gives students and teachers much more freedom to allow experimental design to develop.
Arguments for asking students to follow a fixed method:
- Sometimes the results really matter, and if students design a method that just won’t get the results you want there is a danger of them taking home the wrong message from the practical.
- There are some procedures which are commonly used and asked about in examinations at GCSE and A-level – being familiar with these methods buts exam candidates at an advantage. Examples include bubbling pond weed (very common in KS3 SATS papers and GCSE Biology papers), transpiration experiments, mass change in potato chips etc.
- This puts less of a burden on the technician – I know our technician despairs of me sometimes when I invade the prep room several times in a lesson because students have asked for weird and wacky pieces of equipment to conduct an experiment. Leaving the lab to go to the prep room might not be practical in some schools. I’m lucky that my lab is connected to the prep room so I can wedge the door open and pop in an out to get whatever students ask for. I’ve avoid this in the past by asking students to design their own method in one lesson and submit an equipment order to do the practical next lesson.
- Following instructions carefully is a skill in itself – it’s one of AQA’s competencies which my sixth form students are working on.
- In real world science, replicating a fixed procedure is done to check for the reliability of results.
- From a selfish point of view it’s much easier to manage a class of students doing a fixed producre and it’s much easier to mark.
Although it looks like there are more arguments for using a fixed method, I most of these arguments are not student centred and I think every decision made in the classroom should be for the benefit of the students. I’m all for maximising opportunities pre-GCSE for students to design their own practicals.