I love misperceptions in the classroom. More specifically, I love it when they are exposed in the classroom. More correctly, I can’t teach effectively unless I know what those misperceptions are. When I notice a misperception that comes up in more than one semester, I have a list I put that on. My teaching generally starts from that list.
Here is one that I finally noticed as being a general misperception; consider the following graph of the growth of the garden gnome population at my house ( I would show real graphs, but they are copyrighted):
The question: what is the carrying capacity of my yard for garden gnomes. That is to say, what is the maximum number of gnomes that my house can sustain (key word there).
Here is what a lot of students will tell me: 33 or 34. Despite 6 years worth of data showing that we have sustained about 20 gnomes, they give more weight to the more recent data point. I swear I have seen this when students look at other graphs too, trusting more recent data to the point of throwing out a significant number of points that are older and tell a different story.
Whats that all about? Why is more recent better? Is this some sort of “progress fallacy”?