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Math class is not for reading, apparently

January 20, 2012

Let’s play an annoying game! Let’s play the “Are you as smart as a common fifth grader” game! Here comes the question: a ship is transporting 26 sheep and 10 goats. How old is the captain?

Huh? I don’t know about you, but me, I’ve no idea how old the captain is. But according to this article from the German magazine “Der Spiegel”*, most primary school students are quite sure of the answer. The captain is 36 years old. It seems that the kids quickly learn that math class isn’t for reading, but for doing sums. So, blah blah blah 26 blah, blah blah 10, blah blah blah blah blah? 26+10=36. Easy!

Some researchers from Dortmund** came up with an even more interesting trick question, namely: a 27 years old shepherd has 25 sheep and 10 goats. How old is the shepherd? Well, 27 years old, duh. Only, most kids would start to do sums in this case too. After all, why would anybody bother to mention the sheep and the goat, if it has nothing to do with the problem? And since it’s a math problem, of course something has to be added to something else.

The saddest/funniest case still has to be this dialogue (my translation):

Teacher: You have ten pencils and twenty crayons. How old are you?

Julia: Thirty years old!

Teacher: But you know very well that you’re not thirty.

Julia: Of course I do. But it’s not my fault. You gave me the wrong numbers.

What can I say? I remember our teachers at university drilling us in never forgetting the units, numbers can only be added if they have the same unit. Maybe that ought to be started somewhat earlier?

ETA: To be fair, as a university student I was using a tactic somewhat similar to what the school children in the article are doing. If I didn’t know how to solve a physics problem, I would check the units of all data given in the problem, as well as the unit of the desired result. Then I would try to combine the units of the data to form the unit of the result. When I had it worked out, I would put in the numbers and calculate. It pretty much always worked and didn’t require any understanding. Simple example: How much energy does it take to keep a 40W lamp lit for five hours? Given data: the lamp has an effect of 40 Watt. Lit for five hours of time. Desired result: Energy, unit of Watt-hours (Wh). Watt times hour gives Wh. Aha, I’m supposed to multiply the numbers. 40W x 5h = 200 Wh.

Then it became time for the courses in chemical engineering. Chemical engineering professors are very fond of using so-called dimensionless numbers to characterize their reactors. Dimensionless numbers don’t have any units, making the above trick worthless. It’s one of the reasons I didn’t like my chemical engineering courses all that much.

* “Der Spiegel” means “The mirror”. It’s supposed to be a mirror of the world, I presume.

** The article talks about researchers from the Technical University of Dortmund, and work they did in the nineties. This is nonsense. In the nineties, the university in Dortmund was a plain University of Dortmund, they didn’t rename themselves into a technical university until much later. I find this kind of retroactive renaming somewhat weird. It’s the same with me and my name. I recently had to request some documents from Sweden, and when they arrived, they stated that Ester Lüken paid into unemployment insurance in Sweden between 2005 and 2010. Sorry, no. I didn’t marry until I had already moved to Germany. Back in Sweden I was insured, that’s right, but not under that name.

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