Monthly Archives: September 2016

I’ve often taught Science as a way of thinking critically. That is, science education has (at least) two aspects. First, is the content knowledge. This is necessary because it’s not always necessary to reinvent the wheel. If every person had to start with their own tabula rasa and fill it themselves, without the help of those who came before, progress would be non-existent. Further- and this leads into the second aspect, prior knowledge provides a proving ground for developing critical thinking.

For example, every introductory biology class spends a decent amount of time talking about photosynthesis and cell respiration. Just memorizing the pathways is not enough to actually learn anything. In fact, it’s probably the quickest way to ensure that you don’t learn. Instead, it’s useful to talk about how this pathway was discovered.

von Helmont

Instead, it’s useful to talk about how this pathway was discovered. What was the question that people sought to answer? What was known /thought / assumed initially? What were the first (apparently unsuccessful) experiments done to address the question?

Jan Baptist von Helmont did one of the first good experiments to ask the question: Where does a tree’s mass come from?

He used a willow tree for his experiment and monitored the mass of the tree, the mass of the soil, and the mass of the water he gave it. Because the mass of the soil changed very little, while the mass of the tree grew enormously, he concluded that the tree’s substance came from the water he provided. In his own words, “But I have learned by this handicraft-operation that all Vegetables do immediately, and materially proceed out of the Element of water onely. ”

(It is notable that von Helmont recognized, in other experiments, that carbon dioxide was released from burned wood. He called this ‘gas sylvestre,’ referring to the Latin term for wood / forest, silva. This is important because the majority of a tree’s mass comes from the carbon dioxide in the air. von Helmont didn’t do just one experiment in his lifetime, after all.)

The importance of these historical experiments is that it allows the student to consider, ‘if I were in this person’s position, knowing what he or she did, how would I go about asking such a question?’

It was with this in mind that I came across this video on critical thinking, which I would say is the true value of science.

The topics we ask questions about depends on our interests. Perhaps today we are interested in where the mass of a tree comes from and we’ll be biologists. Perhaps most of the time we have a driving interest in the way that molecules interact, so we are primarily chemists. Regardless of the topic, we use the same critical thinking and experimental procedures to answer our questions, so we are really all scientists.