I repeatedly found that teaching is an exercise in a crowd sourced game of telephone. If you give one set of instructions to a class of 30 you’ll get 30 interpretations of those instructions. I am teaching a Microbiology lab. This week we studied how bacteria grow. Students had a control flask and a second flask that had antibiotics added to it when the bacteria started growing exponentially. They sampled both flasks at 10 minute intervals so they could see how fast the bacteria grew. One group had a sampled their control and antibiotic flask in series rather than simultaneously. I think most people would not be phased by this. But it was bewildering to me at the time as a scientist. It got my thinking about why I was so surprised. It was because of the unconscious expertise and experience I have accumulated as a scientist.
For the non-scientists, most experiments try to pair measurements when possible so they are directly comparable. This is especially important when the study parameter changes quickly. For example, if you were to measure a person’s heart rate every second matters. You can be at a normal heart rate now and elevated in 2 seconds when a mouse runs across the room. Similarly, bacteria grow quickly and measuring 5 minutes apart rather than at the same time reduced the utility of the results. It makes them not directly comparable and makes it more difficult to do statistics.
The students of course had no idea of any of this. I think its amazing how much we have packed away in the back of our brains that we never think about. Things we have figured out and convert into regular patterns of behavior that can be complex. Such as taking off gloves without touching the outside to prevent the spread of infection. Or structuring scientific sampling in the blink of an eye. The brain is weird and wonderful.