I’m sure you’ll get the answer to the first question right. The water in the container with the widest opening will dry about first.
What about the second question? What’s the reason? We all know the answer. Yes, we already know the answer. The bigger the surface area of the water that is exposed to the air, the faster the rate of evaporation. That is also the “correct” answer given at the back of the book.
But wait a minute. The sort of questions that our examiners ask our P6 kids must also stimulate their inquiring minds and they did a self-sabotage by asking the third question. Is this a fair experiment to show that surface area is the factor that is at work here? If you’d started off designing an experiment without any knowledge that surface area affects rate of evaporation, will this experiment prove your theory?
What about the shape of the container? Assuming that you are exploring unknown territory, can you be sure that the shape of the container is not the factor that is affecting the rate of evaporation? In order for the experiment to be fair, that “shapely” container should not be included. Right, teachers?
Next question. And this came from an official school worksheet. Testing the student’s understanding of the principle that light travels in straight lines, 4 different “views” are offered. The “correct” answer is 4.
Wait a minute. Can you see through tube B? Well, if it’s a curved (convex) mirror like what we have located at bends in carparks, then certainly you can see around the bend. But if it’s a plane mirror, then it’s not so certain. Yes, shape matters in this case.
© Chan Joon Yee
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