Monday, 23 March 2015

16 practicals at GCSE

I have stated that I would like to see a curriculum where the content would lead to good quality practical work. There is no point in stating that students should learn about reproducibility if there is no content that lends itself to this sort of experiment. 

The question is do students have to do the experiments to best understand the content? Possibly not in quite a few cases. 

I do think that the statements could be clearer about what they mean. I know that it sounds like a good idea to make things flexible so schools can decide how to meet the criteria, but if an aim is also to ensure that schools do fund practical science appropriately then why not state exactly what is expected? 

To me chemistry seems fair enough, I think my biology knowledge is lacking and this is why I am struggling with this set of topics. There is a statement in the physics section I don't understand, I have highlighted this is red. 

Even before we think about how to assess this skills I think I have to think about how to give the students the opportunity to develop them. I would like to avoid hoop jumping and help students explore science ideas through practical work. I imagine that time pressure and the drive for results will mean that time on practicals will be bumped for time doing paper based questions.

Practical techniques to be demonstrated by Learners in Biology:
  • use of appropriate apparatus to make and record a range of measurements (to include mass, time, temperature, volume of gas produced, distribution of organisms);

  • use of a Bunsen burner and a water bath or electric heater for heating;
This would be covered when doing experiments to discover the optimum temperature for enzymes. I do think it is important to understand why animals and plants usually live in certain temperature zones and those that don't have adaptations. It is useful to understand limiting factors in photosynthesis too.

Volume of gas produced might include the bubbles from pond weed caught by the funnel under water. 
  • measurement of pH and oxygen levels using a variety of techniques such as indicators, a pH/oxygen meter or a pH/oxygen probe and data logger;
Does this include pulse oximeters when studying health? Or the levels around a plant to judge when it is photosynthesising? Does pH mean changing the pH of soil like we used to do in Year 9? Or is it related to enzymes? I suppose it could relate to environment and ecosystems and how the oxygen levels of water affects the 
  • use of qualitative reagents to identify biological molecules;
As enzymes are part of the specification students could test to see if the enzyme has broken down the starch. Again they could test leaves for starch as part of the photosynthesis topic. I am not really sure what else can be tested for outside of food tests? Perhaps testing for carbon dioxide would be included in this. 
  • measurement of rates of reaction by a variety of methods such as production of gas, loss of mass, uptake of water, colour change of indicator;
Transpiration could be included in this. But I am back to enzymes again. I am at a loss to see where loss of mass fits into biology. 
  • choice and use of appropriate laboratory and field apparatus for a variety of experimental investigations;
Ecosystems does appear in the national curriculum so doing field work will be linked to the curriculum, it states: "methods of identifying species and measuring distribution, frequency and abundance of species within a habitat", which would link directly to that statement above and below.
  • use of sampling techniques in fieldwork to investigate the distribution and abundance of organisms in an ecosystem;
  • safe and ethical use of living organisms to measure physiological functions and responses to the environment;
The woodlouse choice chamber experiment could be done here as students do need to know how factors affect communities. My limited biology would say the two are related, just about. I do think that this one could be done better through case studies and not by practicals, especially as choice chamber practicals can be difficult without strong technical support. 
  • use of the light microscope at low and medium power;
Using a microscope would fall into the section on cells. It would be nice to have alternatives to onion and cheek cells though. But it is possible to buy examples of sides already made. 
  • production of labelled scientific drawings from direct observation of biological specimens. 

Practical techniques to be demonstrated by Learners in Chemistry:
  • use of appropriate apparatus to record a range of measurements (to include mass, time, volume of liquids and gases, and temperature);
  • use of a Bunsen burner and a water bath or electric heater for heating;
  • measurement of pH using pH charts and digitally;
  • collection and identification of products of reaction and measurement of rates of production;
  • safe and careful handling of gases, liquids and solids;
  • careful mixing of reagents under controlled conditions using appropriate apparatus to prepare substances;
  • use of a range of equipment to separate chemical mixtures: to include evaporation, filtration, distillation, crystallisation, chromatography, electrolysis;
  • collection and analysis of products from a simple electrochemical cell;
  • use of appropriate apparatus to determine relative concentrations of strong acids and strong alkalis. 
I believe that the chemistry techniques link the national curriculum much more easily. It lends itself better to practical experiences.

Practical techniques to be demonstrated by Learners in Physics:
  • use of thermometers and electrical measuring instruments, with heating and cooling devices, to explore energy transfers as temperatures change and to explore phase changes;
Traditionally at key stage 4 we would look more closely at specific heat capacity and revisit the methods of heat transfer. Perhaps here students could investigate insulation and cooling curves and compare situations that would allow conduction/convection and those that would reduce it. They could also investigate the colours of cans that are loosing heat. Energy transfers could be investigated using E=VIt to work out the energy supplied by a heater and this can be related to specific heat capacity and ultimately the efficiency of the system. A series of lessons on energy transfers involving heat could help students to understand that heat is transferred from areas of higher temperature to areas of lower temperature and an appropriate model could help students appreciate the relationship between kinetic theory, temperature and heat. 

Ideally this would be possible in core science, but we only get a few lessons to teach this, will it be possible to really explore this in the new curriculum? 
  • use of measures of weight and direct and displacement methods for measuring volumes to determine densities of solid and liquid objects;
I am pleased to see that upthrust is part of the GCSE curriculum, otherwise there would be little point in this. I don't see how you can teach this and help the students to grasp it conceptually without putting objects in water. I like to plot volume (cm3) against mass (g) and see the relationship between the objects that float and those that sink - think about it. Then calculate density and see what it means. I hope that density is in the new specifications as I do think that it is an important concept to grasp. Teaching this after teaching particles will help as it is easier to see 'less particles in the same space = less density" than think about mass, which is a slightly abstract concept. 
  • use of instruments to measure distances and times: to determine speeds and accelerations both in laboratories (for example, motion of a mass down a slope, or of a mass projected by a compressed spring) and in everyday motions (for example, walking, running and cycling); 
I find this deadly dull. Timing yourself walking or timing a ball rolling down a slope is not my idea of fun and I also don't think that students really need to do this to understand and it detracts from teaching time. I always find students working out acceleration tricky too. I can see some of the vernier iPad applications being useful for this though, and that might peak the interest of students more. Perhaps the ticker time needs to be brought out of the back of the cupboard? Hopefully not, but a class set of data loggers is expensive for once per year. 
  • to explore transmission and reflection of sound waves;
Does this mean that the have to go outside and make an echo? I don't get it. 
  • measure speeds of both sound and of waves on water, and the wavelengths and frequencies of waves on water;
I have never done this as a practical, are my students missing out? I have recently discovered a thing ripple tank, perhaps I should be buying a class set. Although I can see gratnel trays and lamps being used, or simulations and demonstrations.  
  • use of low-voltage power supplies, ammeters and voltmeters to explore the characteristics of a variety of circuit elements;
I am glad this is making a return to GCSE, I love making circuits and helping students to understand models within electricity. 
  • construction of both series and parallel circuits from circuit diagrams using DC power supplies, cells and a range of circuit components, including those where polarity is important; representation of the circuits used with conventional symbols;
I was slightly concerned by this as the national curriculum does not mention diodes, but the GCSE criteria does, so this is possible. Time to do V vs I graphs for bulbs, diodes and wires might need to be found. I usually do one as a practical and demo the rest. 
  • connection, or checking, of the three wires for an AC mains plug and checking of the way these wires are connected to a domestic device;
Really? Still? It is actually quite dangerous if you can't trust your class or can't put a rivet through one of the pins on the plugs they are wiring. Easier to copy from a book. However, it is part of the GCSE, which is good and I have the ability to do it. 
  • safe and careful handling of electrical power supplies, experiments involving accelerated and uniform movement of objects, and effects of steady or oscillating light sources;
What on earth is this one all about? Is it three sections or one? 
  • use of springs and strings with weights to explore linear, non-linear, elastic and inelastic stretching;
Compressing and stretching is part of the GCSE content. 
  • use of iron filings and magnetic compass to explore fields of magnets and of electric wires and solenoids. 
I will have to find out if we have a class set of westminster supplies to do this practical with. I HATE iron filings, terrified of getting them in eyes. The practicals are on the practical physics website however, and they do related to the curriculum, which is good.

I would have liked to see reflection and refraction and measuring critical angle in here, but it doesn't seem to be an explicit part of the new GCSE criteria, which I am a little upset by. I think it's important as a foundation for A-level. 

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