Saturday 10 November 2012

Past And Present

One of the things most likely to get me into Mama Bear-mode is criticism of modern A-levels that suggests that students are getting worthless qualifications. I frequently find myself having to remember that it is frowned upon in polite society to punch the lights out of ignorant wankers telling you that your students are stupid and that teachers are failing them. With the proposed end of January A-level exams, the opportunity presents itself for idiots to weigh in with their opinions.

I imagine the Daily Fail has been saying exams are getting easier since exams were invented, but it certainly seems that this has escalated in recent years. I've mentioned before that I acquired my past exam papers, and I had a fantastic opportunity to do a small test with my A2 students a few weeks ago. We had just finished looking at photosynthesis, so I copied a question from my 1997 Central Concepts paper.
A cell suspension of a species of Chlorella, an alga, was supplied with carbon dioxide, initially at a concentration of 3%. This was then reduced to 1% after 100 seconds, and then to 0.03% after a further 200 seconds. The levels of RuBP and GP (PGA) present were determined at intervals.

(a) With reference to the figure, state the effect on:
(i) the concentraion of GP when the carbon dioxide concentration is reduced from 3% to 1%. [1]
(ii) the concentraion of GP when the carbon dioxide concentration is reduced from 1% to 0.03%. [2]
(iii) the concentration of RuBP when the carbon dioxide concentration is reduced from 1% to 0.03%. [3]

(b) Explain the observed change in the concentration of RuBP during the 100 seconds immediately after the carbon dioxide concentration was reduced to 0.03%. [4]

(c) State the evidence provided by the figure which indicates that the concentration of carbon dioxide may not be a limiting factor. [3]
Then I gave my students one of the Edexcel questions from June 2012, with a remarkably similar graph.
An investigation was carried out into the effect of reducing the carbon dioxide available for photosynthesis. Cells of a unicellular alga were suspended in a solution containing 1.0% carbon dioxide. After 250 seconds, the carbon dioxide in the solution was reduced to 0.003%. The cells were illuminated with a bright light and some were removed at regular time intervals for 500 seconds. The concentrations of ribulose bisphosphate (RuBP) and glycerate 3-phosphate (GP) in the cells were measured.

(i) Suggest two reasons why a suspension of cells of a unicellular alga, in a solution, is more suitable for this investigation than using leaves. [2]
(ii) Suggest why it would be advisable to illuminate the cells at a high light intensity during this investigation. [3]
(iii) The graph below shows the results of the investigation.

Describe and suggest an explanation for the changes in the concentrations of RuBP and GP shown in the graph. [6]
So, which paper do you think the students found easy? Why, that would be the 1997 paper. The majority of the questions involved very little mastery of the subject knowledge. I imagine a numerate non-scientist could do quite well on the 1997 paper, just reading off the graph. The A2s preferred the clarity of the graph in the 2012 paper, but I think much of that can be attributed to it having been reduced from A4 to A5 and scanned.

The "suggest" questions in the 2012 paper involve students applying their existing subject knowledge to an unfamiliar experiment. The final six-mark question is a QWC question, meaning students are not only assessed on their biological knowledge, but their ability to present it clearly and logically. My A2s hate QWC questions, and they really hate "suggest" questions; because they have to show an excellent command of the subject, rather than being able to pick up marks for stating the bleeding obvious.

Sure, this is only one example. But I bet colleagues in other subjects can show where the exams are indeed more rigorous, demanding more detailed subject knowledge, a greater degree of critical thinking, and the ability to apply all of this to new situations. Gove and Co have spent so long chipping away at the exams my students sit, telling them their coursework is nothing more than teacher-sanctioned cheating, that they don't work hard because they know they can always resit their exams, and that modular exams are too easy. They claim to want more rigorous exams, but as Paul said, in the spirit of Inigo Montoya, they keep using that word; we do not think it means what they think it means.

So here's a multiple-choice question to the Department for Education. How should students be assessed in the academic pathway before leaving school or college?
(A) A combination of practical and written exams and coursework, enabling students to demonstrate complex subject knowledge and application, with opportunities to resit units, reflecting the way that pretty much every university degree, and indeed every assessment they will face in life, is set up.

(B) A single terminal exam in each subject, requiring students to memorise facts, definitions and explanations, with no resit opportunities.
Option B seems to be what Gove wants. But I don't think it's what any student or any teacher wants.


  1. How the hell did they get back in?

  2. Good thing you've mentioned here this super green alga known as chlorella. I think that the Department of Education should also teach students about the health benefits of these biology samples. They can even discuss chlorella benefits because these are really good source of health advantages.

    1. See, normally I just delete these spam comments, but I've decided to leave this in just so any students (past or present) of mine can see my view that the idea of Chlorella providing any benefits beyond a vague carbohydrate source is utter bollocks. The Department for Education is highly unlikely to make the non-existent health benefits of Chlorella a key point on the A-level curriculum any time soon. I would sooner teach Lamarckism.

  3. Ah, those spammers! Mountebanks of the 21st Century!

    Right, update on that Arum: 1 plant turned out to be three. All were transplanted to a pot. One's dying of transplant shock, one's mediocre, and the third is doing famously. That third one has greened up nicely and is even shooting new leaves. A fortnight and it'll be in a fit state to transport, so if you want to pick a date and time for about a fortnight from now then I'll drop it round.

  4. I've been lax in not pointing you at Crash Course. Fortunately the latest episode was on Ecological Succession, so I suddenly remembered that you should probably be aware of them. I think they're probably most useful to your students as revision aids. But they're pretty fun in and of themselves.


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