Textbooks and Teachable Moments

Today's Lesson: Using Your Textbook - and, of course, basic background on atoms, electrons, and protons. Have you seen a middle school science textbook recently? They are packed with facts. The vocabulary and sentence structure is pretty advanced. And they sometimes assume knowledge that they have not yet taught, such as the section we read today that refered to the fact that opposite charges repel, although that information is not presented until the next section. Children don't necessarily know how to use a textbook - how to understand the different levels of titles and headings, how to use the sidebars to supplement and guide their reading, what to do when the text refers to a diagram, how to use the glossary. So, we read a page of the book and went over all these nuts-and-bolts elements of textbook reading. I only have one class set of textbooks, as I prefered to spend my budget on hands-on materials. I use it sparingly, and provide support for the kids' reading.

For kids who have not yet learned much about atoms, just one page contained a huge amount of new information - we easily filled a period discussing the nucleus, the different particles, and the difference between an atom and an ion. Very simply, an ion is an atom with an imbalance of charges, thus, a net positive or negative charge. Ions are the reason that water will conduct electricity when it contains salt: the salt and water molecules break up into charged ions: Na+ Cl- and H+ OH-.

Yesterday, we finished our first real experiment: the students designed circuits to test whether various objects could conduct electricity. We finished off by testing whether water could conduct electricity. We tested beakers containing water only, water plus a spoonful of salt, water plus two spoonfuls of salt, and so on. The first time through, none of the solutions conducted electricity. The kids were surprised - doesn't everyone know that water conducts electricity? Why else would you have to get out of the pool during a thunderstorm? Why the elaborate warnings on hair dryers? We came up with some theories: maybe there's not enough salt, or not enough electricity. The latter turned out to be true: when we combined two batteries, the light shone dimly. We experimented further, and found that six batteries made the bulbs shine brightly. Oooohhhh! The kids exclaimed in unison when the light came on. Fantastic! I seized the moment and suggested that a group could follow-up on this experiment for a Science Expo project this spring.