Moving Beyond Predict/Observe/Explain

25Feb14

I don’t remember when I first used the idea of breaking down a demonstration for students by having them follow the POE format:

  • Predict what will happen
  • Observe what actually happens
  • Explain it in context

I think a lot of science teachers used this before – or even without – referencing the ideas of Michael Bowen, who explains the approach in this video. He wasn’t the first, but I tracked down the link via the site of the National Science Teachers Association in the US. There are several papers available there, for example this from a decade ago about hypothesis-based learning, which makes explicit the difference between a hypothesis and a prediction. It’s easy to see how these steps link nicely with a 5/7Es planning method. But I think it’s worth adding some steps, and it’s interesting to see how it might have developed over time. How students cope with these stages is an easy way to approach formative assessment of their skills in thinking about practicals, rather than simply doing them.

Please note – I’m sure that I’m missing important references, names and details, but without academic access I simply can’t track original papers or authors. My apologies and please let me know what I’m missing in this summarised family tree!

PEOE: I think this because

To stop students making wild speculations we need to involve them in a conversation justifying their predictions. I suppose this is a first step in teaching them about research, to reference their thoughts. I find this needs guidance as many students mix up the two uses of explain; the derivation of their prediction and the link to accepted theory.

PODME: Recording what we observe

I got this from Katy Bloom (at York SLC, aka @bloom_growhow) I think after chatting at a TweetUp. I’m paraphrasing her point: in Science it’s not enough simply to observe, we must also share that observation. This can take two forms, Describing in words and Measuring in numbers. The explanation then becomes about the pattern rather than a single fact or observation. Bonus points to students who correctly suggest the words qualitative and quantitative for the observations here!

PBODME: My current approach

I’ve tweaked this slightly by making the first explanation phase explicit. The display is on the wall and students can apply this (with varying degrees of success) from year 7 practicals with burning candles to year 13 physics investigations into gamma intensity affected by thickness of lead shielding.

  • Prediction of outcome
  • Because of hypothesis based on life experience, context or research
  • Observation using senses, measuring devices
  • Description in words of what typically happens (sometimes as commentary during practical)
  • Measurement using appropriate units, with derived results and means where needed
  • Explanation of results, patterns, anomalies and confidence

Is it getting ungainly? Having this structure means students can see the next step in what they are doing, and are hopefully able to ask themselves questions about how to develop a practical further. I suppose you could argue that the original POE approach is the foundation, and these stages allow us to extend students (or ideally allows them to extend themselves).

PBODMEC: Why does it matter?

In many ways, the natural next step would be about Context – why should we care about the results and what difference do they make to what we know, what we can do or what we can make?

I plan to follow up this post with the printable resources (wall display and a student capability checklist) but they’ll have to wait until I’m home. In the mean time, I’d welcome any thoughts or comments – especially any with links to other formats and their uses in the school science lab.

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14 Responses to “Moving Beyond Predict/Observe/Explain”

  1. A useful reference is a chapter in Probing understanding (White and Gunstone, 1992) http://www.amazon.co.uk/Probing-Understanding-Gunstone-University-Australia/dp/0750700475
    They make the point that it is helpful to students to write down what THEY observe before speaking about it, otherwise they may ‘see’ what the persuasive folk see.

  2. Sorry, I also meant to say that I like your interpretations of what goes into the three stages of the to the original POE.

  3. I like the “because” near the start of this being different to the “explain” at the end; and the fact that you’re using explain not evaluate. I always found the concept of evaluation in science hard to get over to students who were used to it meaning “how do I feel about my outcomes?” in other subjects.

  4. I’d like to take this opportunity to promote the “Get set…demonstrate” campaign, run by the British Science Association, with the support of the Gatsby Foundation. The campaign aims to encourage secondary teachers and technicians to get more out of science demonstrations and also give them resources to improve their activities. We’ve created six high-quality demo video guides with accompanying written guides. Moreover, we’re celebrating 20th March as Demo Day, and everyone who pledges to participate will receive discounts on demo equipment from Timstar, as well as free access to Twig World’s new Twig Experiments. Please visit the campaign’s website for more information: http://www.getsetdemo.com.

    • Fantastic idea – I see StoryCog and ScienceDemo.org are involved which is always a good sign. I wonder if it would be a good focus for a Monday discussion on #asechat? I tried to get a ‘tips and tricks’ hashtag running a while back but it – sorry for the pun – burned itself out.

      • 6 @maryUYSEG

        I think there will be an ASEchat in a couple of weeks on demo the movie

      • #ASEChat 17 March 8.00pm for ‘the Demo’

      • Yes, we’ll be hosting #ASEchat on 17th March (@ScienceWeekUK) to discuss demonstrations, with the discussion particularly focusing on the soon-to-be released short documentary “Demo: the Movie”. We’ll circulate where online to watch the documentary in advance!

  5. I’ll throw in here and hopefully get some debate on what I think is a problematic area for science teaching.

    Science practical work has many intended outcomes, but in a ‘scientific’ sense it is about the testing of a hypotheses. Of course in the classroom there is a huge tension between the forces of of teaching the content required and teaching and students using a scientific approach to understand the world. Take the classic ‘testing food groups’ practical. What is reallreally being done here? Mostly its about the identifying which foods contain protein, sugar etc. and developing practical techniques. Both are valid aims, but in terms of are not really experimental.
    I think many science practicals fall broadly into this area. To turn it into something experimental isn’t a huge step, but does require some caveats. Using a system similar to your model, I suggest that the observation could come first. In the food example, the observation could be ‘biscuits taste sweet, when tested with Benedicts reagent they contains sugar’. Of course this requires some student knowledge of sugar and the Benedicts test, but at least fits their model of things being sweet.
    The key point then becomes the hypothesis. This is also the difficulty, since their are an infinite number of hypotheses available. The teacher can easily dismiss most of these, but the students will not find this task so easy. I suggest here trying introducing approaching a simplified null hypothesis approach – for example “only biscuits contain sugar”. The practcal then becomes an attempt to contracdict the statement, much closer to a scientific approach. It also leads to much more opportunity to bring challenge the assumptions (foods they wouldn’t expect to contain sugars, foods with sugar but not reducing sugars).
    This doesn’t seem like a massive variation from your extension on POE, but it is making a subtle change. Putting the observation first and then testing the hypothesis forces an explanatory component. It will still require teacherguidance but is altering the student’s perception of the purpose of experiment – to empirically test a hypothesis to guage its explanatory value. It would also include limits to the experiment (you didn’t test all foods, what is meant by sugar). It would also add value to reults that don’t go according to a students expectation. It would require a rethink of some of experiments and reframing their purpose but could result in getting a lot more from experiments.

    tl;dr observe, hypothesis, describe, measure, explain

  6. I like everything in this post but perhaps the key thing that comes out of all the literature on making practical work more effective is that careful thinking about the LOs is crucial before starting to plan the practical. So, are you using this to help pupils learn about the process of carrying out an investigation, or are you using it to help them develop conceptual knowledge? Or do you use the same approach for both? My feeling is that your approach outlined here is a superb way to approach investigations but that the POE at the top, or PEOE, pares back to what is required for developing conceptual knowledge (although, the O would sometimes need to involve observing/making simple measurements rather than just watching).

    • Absolutely – you could argue that my extra steps are more about making the implicit ideas more accessible to students, rather than a real difference. I would say the same to you as to Jonathan; this is only one way to get kids thinking about practicals and demonstrations. I blogged a while back about just these ideas actually, about the different skills we intend to teach kids. https://teachingofscience.wordpress.com/2012/01/18/demonstration-or-class-practical/ Thanks for your thoughts – think the great comments on this post will inform my follow up!

      • Thanks for that link. I really like the idea of a checklist to decide practical or demo. I agree with all the choices on your list but I think maybe the key thing for conceptual understanding is whether or not the concept drops easily and convincingly out of the data. The classic example is Kirchoff’s 1st Law which is often obscured by overly precise ammeters, contact resistance, pupils getting their circuits wrong, and the odd blown bulb, damaged wire, or loose connection.

  7. Hi Carol
    We were using POE techniques for teacher development activities within the CLIS project in 1987, so your research needs to go back quite a long way to find out who first documented the approach. Try Richard Gunstone and Monash as a starting points.
    I have a copy of Predict, Observe, Explain (2010) John Haysom, NSTA if interested


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