Wednesday+(Phase+change+and+energy)


 * BELLWORK (Including character education, ACT math and vocabulary)**

“The individual has always had to struggle to keep from being overwhelmed by the tribe. If you try it, you will be lonely often, and sometimes frightened. But no price is too high to pay for the privilege of owning yourself.” Friedrich Nietzsche
 * Quote**

Elate //–verb (used with object)// //–adjective = elated.//
 * Vocabulary**
 * 1) to make very happy or proud: //news to elate the hearer//


 * CLASS ACTIVITES**

The once the quote and the vocabulary are copied and discussed the following questions will be projected on the screen:
 * Change of phase**

a) Air. b) Oxygen gas and hydrogen gas. c) Oxygen. d) Water vapor. e) Heat
 * In a pot of pure boiling water. What is in the bubbles in the boiling water?**

a) Water is pushed through the glass b) Water moves around the glass c) Water comes out of the air d) Water is pushed out of the glass
 * When you leave a cold drink on the counter on a hot day how does the “sweat” form on the glass?**

As I discovered on the pretest, many of the students know the answers to these two questions. As a result, I was able to move through this material quickly.

To show the students that condensation and freezing are exothermic processes I cooled a hammer in a container that holds my dry ice. When I removed the hammer from the dry ice the hammer was VERY cold. We observed what happened to the surface of the hammer once it his removed from the dry ice. The students made and recorded their observations. Obviously, the hammer formed a layer of frost. Once this happened we talked about it as a class.
 * The very cold hammer**

We next physically modeled the very cold hammer. We reviewed what we learned at the start of the school year regarding states of matter and motion; Gasses move around rapidly and bounce off of each other, liquids move around but stick to each other, and solids shiver in place. At this point we cleared the desks out of the middle of the class and modeled solid, liquid and gas behavior. //(when we a child is modeling gas behavior he moves in a straight line unit he encounters another student or wall and then bounces off. When a liquid he moves randomly, but must in contact with another student. When solid he shivers in place near other students.)//
 * Modeling the very cold hammer**

Next we applied the concept of energy to these states of matter. I asked “Which state of matter has the most energy?” The kids understood that the gas phase does. We then used Styrofoam spheres to represent energy and modeled what happened to the very cold hammer. I asked “What will happen when a gaseous particle of water strikes the very cold hammer? What will happen to its energy, where will it go?” //(A student who is modeling water vapor has three Styrofoam spheres, 2 liquid water, 1 or 0 is solid water, or ice. As “water vapor” students encounter “cold metal” these students shed their spheres [energy] and the metal warmed up, but the water freezes) Most students understood this immediately and very little explanation was required to prove that freezing is an exothermic process.//

//Several doubters were insisted that freezing made things cold still. I asked, “What would happen if I poured molten iron on your face?” The responded that their face would be burned. I then asked, “Wouldn’t the iron cool into the mold of your contorted face?” They once again responded in the affirmative. This seemed to clear that up.//

The ideas of condensation and freezing were introduced today. Likewise, their opposites—melting and evaporating—were also introduced. We defined the terms endothermic and exothermic and label each process as being ether endothermic or exothermic.
 * Terminology**

We were able to push through the first part of class quickly and I found myself with extra time on my hands. I took this opportunity to teach the students about phase diagrams. I show the students a few phase diagrams and had them interpret a few unlabeled ones in groups. Phase diagrams are not particularly challenging and the students soon mastered them. I showed them a 3-D phase diagram with Density on the z-axis. That got a few of them thinking, but many were intimidated an simply gave up. This took up the rest of class.
 * Phase diagrams**

I’m sure that most of the class will think that “air” is in the bubbles at the bottom of a boiling pot of water. I also think that a good number of students will write that the sweat is coming from the water in the glass either by being pushed through the glass or coming out of the glass.
 * __What I expect__**


 * Reflection**
 * Turns out I was wrong. The students knew a lot more about these questions going into the lesson than I thought. As a result of this I covered the concepts of endothermic and exothermic physical changes very quickly. I got the chance to adapt my lessons on the fly by throwing in phase diagrams to fill in the last 40 minutes of class. This freed up all of Friday to play. It’s a good thing too. Only about 1/3 of my students showed up to school on Friday.**