Much of what is covered in introductory Science is simplified. It is simplified for a reason – the full explanation is complex, involves higher level mathematics, or concepts that have yet to be learned. In most cases I explain to my students that we are working with a simplified model that is sufficient to manipulate the concepts at the level we will be working at, but that if they go on to study this discipline in later years, the topic will be revisited and elaborated. Some keeners want to know more, and I am happy to explain things at a higher level to those who are curious.
But I hate when concepts are simplified to the point of an outright falsehood, especially when it is so obvious that the kids recognize the lie. Take the model of the atom as taught in Grade 9 Science, for example. We are told that as we move out from the atom, the “shells” are able to hold more electrons, and then we are told that the first three shells hold 2, 8, and 8 electrons. Every year I get the same two questions immediately: “If shells farther our hold more electrons, why do those two have the same number?” and “How many does the 4th shell hold?”
So this year, I told them flat out before going into the model that I was going to lie to them. I told them that the information was simplified to the point of being factually incorrect. Then I told them that the shells hold 2, 8, and 8, and that the third shell is the lie. This did a remarkable job of focussing their attention, as now they wanted to know how this “lie” model differed from the “truth” model. So I explained that the third shell actually held 18 electrons (answering question 1), but that the shell had two volumes – volume 1 and volume 2. Volume 1 held 8, and volume 2 held the other 10, but that the electrons in the second volume behave like electrons in the 4th shell, and that it gets complicated. I let them know that if they wanted to learn more about the hows and whys of electron shells, I would be happy to discuss it outside of class time, but since Grade 9 Chem unit only deals with the first 20 atoms, we would stick to the simplified 2, 8, 8 model.
A few stuck around to learn more, but many were relieved that they didn’t have to learn the more complicated model just yet. And I didn’t have to lie to my students. Everyone wins.