# Fall 2009 Day 12

Day 12 Topics

Fall 2009: Day 12
Written by: Katie Kizer

Once again, we started off class by discussing the moon and its phases. Currently, when the moon is out, it appears to be a waning gibbous that is almost a third-quarter moon. As a class, we discussed what we should be seeing in the next couple of days. Michele asked the students to draw a picture of what is going on with the phases of the moon if someone were to be above the earth/moon/sun picture. She asked them to take into account relative distances and sizes when they drew their pictures in pairs. All of the groups drew the moon being close to the earth and the sun being far away, but not all of the groups drew the moon half-lit at each phase. When we asked the class why they drew the moon closer to the earth, they said that they knew it had to be closer to the earth than the sun because sometimes there are eclipses where the moon covers most of the sun, so the moon must be closer to us than the sun. The idea of the moon being half-lit at all times was difficult for some groups to understand because they are used to seeing the moon from their own perspective, on earth.

To further demonstrate that the sun is much farther away from the earth than the moon is, we can use a model with ping pong balls again. Since we know through observation that when the moon is half-lit, there is about a 90 degree angle between the sun and the moon, we can recreate this in class. The students held their ping pong balls out with one arm and pointed their other arm at the sun (the light bulb), making sure their arms were at a 90 degree angle. When they stood close to the light bulb, their ping pong balls did not look half-lit, they looked like gibbouses. To make their models match up with their observations, they had to step farther away from the light bulb. The further away they got (while keeping the 90 degree angle), the more “half-lit” the moon looked. This demonstration indicated that the sun is a very far distance away, and the moon is much closer to earth(the students).

To begin exploring thermal phenomena again, Adam placed about ten random items on a table and asked the class as a whole to categorize the items. At first, the students started shouting out ideas about how they could group the objects by size, color, use, density, etc. They finally decided to group the items by what they thought were good conductors on one end, and what they thought were good insulators on the other. In pairs, the students discussed what these two words meant and how they could describe them. Upon sharing ideas with the rest of the groups, the class came up with a powerful idea to add to the white board: Conductors(metals) transfer heat quicker than insulators(non-metals).

Another activity dealing with thermal phenomena was next. In two groups, the students put ice into a pot that was on a hot burner. They watched the temperature rise with a thermometer. The ice instantly began to melt into liquid form. Once it was all liquid(water), the temperature plateaued for a moment before it started to steam and turn to the gaseous state. Once the water started to turn to steam, the temperature stopped rising. It did not quite reach 100 degrees Celsius. One group found this to be particularly interesting. They associated this to the water having impurities in it. The impurities have different boiling points alone, so mixing the two (water and the impurities) must cause a new/different boiling point to come about.

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