Most of us develop a sort of intuitive logic about how the natural world works. Unfortunately, a lot of that informal reasoning turns out to be wrong, which complicates scientific education. But as students make their way through the science education pipeline, they should gradually start moving beyond the informal reasoning of their earlier years. Or at least that’s what we’d like to think; instead, a new survey of college students, some in advanced biology classes, indicates that most end up with a confused mix of formal and informal reasoning.
The clearest example of the chasm between a typical intuition and scientific reasoning comes from the world of physics. Imagine a marble rolling around a curved track that comes to a sudden end. Physics tells us that, as soon as the marble is off the track, it’ll continue moving in a straight line until it runs into something else. But many people use informal reasoning and conclude that the marble will continue to follow a circular path even after it escapes the track. In other contexts, it involves an interventionist view of the world. As the people behind the survey put it, “When using informal reasoning, students look for ‘actors’ that drive ‘events’ and are aided by ‘enablers.'”
Scientific education, then, needs to convince people to move past their intuitions (at least if they want a more accurate picture of how the world operates).
The article is not out yet apparently (January BioScience is not there yet. Only December.) The write ups seem to indicate even students quizzed in their specialties have ‘intuitive’ answers that are wrong.
This follows up on some of their previous work that indicated that incoming students had serious problems with what they ‘knew’ versus what was real.
I think science education requires a different approach to pedagogy than other fields. In other areas, our intuitive, heuristic approaches to things serve us well. But in science, even educated people can become fooled, especially when not thinking logically, rationally and deeply.
A fun example can be found in the comments regarding one of the questions:
A mature maple tree can have a mass of 1 ton or more (dry biomass, after removing the water), yet it starts from a seed that weighs less than 1 gram. Which of the following processes contributes the most to this huge increase in biomass? Circle the correct answer.
A) absorption of mineral substances from the soil via the roots
B) absorption of organic substances from the soil via the roots
C) incorporation of CO2 gas from the atmosphere into molecules by green leaves
D) incorporation of H2O from the soil into molecules by green leaves
E) absorption of solar radiation into the leaf
Now, these questions are given to people who have had classes in botany or biology and so are well versed in the principles involved, if they have learned to think scientifically.
There was a discussion about the ambiguity of answers C and E. Several commenters though E would be a right answer, since without photosynthesis, there could be no growth. But E does not mention photosynthesis. It simply mentions absorption of solar radiation. There are many processes of absorption, such as thermal, that have nothing to do with photosynthesis. And even photosynthesis uses just a small amount of the total radiation.
E only ‘seems’ like a right answer if you take it to mean photosynthesis. But that ‘intuitive’ answer requires a leap to conclusions. Photosynthesis is not explicitly mentioned. Trying to use it for an answer is a leap not based on real data. Those that answer this question were guilty of making a leap to a conclusion that is not supported by the data provided– a very common error in non-scientific thinking.
Then there was a discussion about C and D. Someone found that photosynthesis performs the following reaction:
Hmm, unless the Wikipedia article on photosynthesis is wrong (6CO2 + 6H2O -> photosynthesis -> C6H12O6 + 6O2), it seems to me that the students are right to suggest that most of a tree’s mass is brought up from the soil (in the form of water). Six atoms of oxygen plus twelve of hydrogen definitely out-mass six atoms of carbon.
Or am I missing something?
There ensued some discussion about the atomic weights of carbon dioxide and water in order to determine whether the water from the soil is more responsible for the biomass or the carbon dioxide from the air. This is a much more productive and scientific discussion, one that actually really occurred in the scientific examination of photosynthesis and biomass.
Looking at the mass equation – which is greatly simplified but useful for discussion – one sees that oxygen is released at the end. Where does the oxygen come from – the carbon dioxide or the water? Even Wikipedia tells us – the released oxygen comes from the water. The only mass water contributes is its hydrogens.
This is one of the key discoveries regarding the process of photosynthesis. Anyone learning about this should remember that bit of data. I remembered this and the last class I took on photosynthesis was 30 years ago.
Biology students should remember this. Water is simply used as an electron donor. Other molecules can substitute for water in photochemical reactions using carbon dioxide.
And the experiments that were designed to show this is true – work that any student should have been taught – demonstrate wonderfully how the scientific method works and the underlying principles for discovery. How do we determine where the oxygen comes from? We use radioactively labeled oxygen in the carbon dioxide or in the water. When the radioactive oxygen is in the carbon dioxide, radioactivity stays in the plant. When the radioactive oxygen is in the water, radioactivity is released into the surround air.
So, to anyone who is taking science courses in biology and who is learning to think in a ‘scientific’ way should have been able to answer the question properly. The largest portion of the biomass comes from the incorporation of both carbon and oxygen from carbon dioxide.
Unfortunately, very few students were able to think these questions through in a way that brought their scientific reasoning to bear. They simply answered with what seemed like the best answer – the ‘obvious’ one, the ‘intuitive’ one – without engaging the parts of the brains most important for scientific thinking. They made a leap to the conclusion without fully analyzing the data provided.
Or they did look at the data provided but forgot the data they had learned and were unable to combine them in a way to discern whether C or D was most correct.
Thus the need to do better with scientific education. Scientific thinking require a rigor and attention to the systems details that is very different from the sorts of thinking we do to live our daily lives. Now we need to do a better job achieving that.