I also offered students the chance to earn some points back on their unit 5.1 quiz--7 points if they can convince a parent/guardian to log onto this site and make a post. My goal is two-fold: one, to let parents know that I am blogging about science class, and two, to reward students for making an extra effort (and to get them looking at the posts as well). I am hopeful that doing this will help parents keep up with our difficult material and help their son or daughter with this great but sometimes difficult subject. Science really is awesome and very important to understand in our rapidly changing world.
I wish that I could take a picture of my fume hood right now to confirm the mess that I made today and yesterday showing what happens when sodium (Na) is put into water (H2O). Sodium is an alkali metal and is very, very reactive, with only one valence electron. When placed in water, it has a greater attraction for oxygen (O) than hydrogen (H), so the water molecule splits and hydrogen gas (H2) is released. The formula for the reaction, which we learned about today in all sections, is Na + H2O --> Na2O + H2 (gas). The activation energy for this reaction is very low, so it doesn't take any additional energy to make it happen. In the L section, I destroyed a test tube for the best demo of the day. In the W section I accidentally set a paper towel on fire, and then a cloth towel (it got hit by sodium, which was wet and still hot--not a good smell). But it all happened in the fume hood, without which I couldn't show this demo at all.
For the WL & S sections today (lesson 5-6), we looked at three EQ's: 5-7: What would be convincing evidence that a chemical change had occurred? Several things, actually. A color change, a precipitate forming, an energy change (exothermic or endothermic), gas given off, and I also added seeing fire and/or smoke. This is not always conclusive proof. Conclusive proof is when a new substance is formed. For EQ 5-8: What is a chemical equation? we looked at the parts of an equation (the left is the reactant side--it reacts; the right is the product side--it is produced). The sodium equation above is a good example. Finally, we looked at how mass is conserved in a chemical reaction (EQ 5-9). Whatever goes in, must come out. We distinguished between an open system that is not contained, and a closed system that is. I showed the disgusting nasty experiments I have hanging on my fume hood--salami, a hot dog, jello, a tomato, and even a pancake. I took a bite out of a nasty rice krispie treat in each section (it was only 8 weeks old--no mold!) and savored the joys of teaching middle school, where nonsense like that still helps students pay attention. I assigned 5-10 and 5-11 for homework.
Here is a video from youtube showing a similar reaction. (This is what makes science fun to learn).
The O section moved on to lesson 5-7. We reviewed combining atoms using the not-so-smart boards (they are small dry erase boards), and then took a quiz on it. Almost everyone got a perfect on the quiz, which made me very happy :) I made sure that we understood it before the quiz, which was a good idea. Somehow this took the whole period, but considering the quiz scores, it was worth it.
And to that I say, sweet justice.
