# Fall 2009: Day 3

Day 3 Topics

Rooftop Explorations
Diameter of the Sun
Ning Websites
Reflections

Peer Instructor Reflection
Fall 2009: Day 3
Written by: Katie Kizer

Today in Physics, we observed the sky. At 9:30 a.m., both the sun and the moon were out at the same time. We ventured onto the roof of Weniger Hall to see them both simultaneously. The students each pointed one arm at the sun and one arm at the moon and estimated the angle between the two to be about 160 degrees. The students also took note of the fact that the moon was not full. As a class, we wondered if the moon would be getting bigger or smaller over the next couple of days. A very neat theory was given to the class by one of the students; if you look at which side is the flattest part of the moon, it should look like a lowercase “b” or a lowercase “d” depending on which side of the moon is more visible. It looked like a “d,” so the moon must be “dying,” or getting smaller. If it had looked like a “b,” it would have been called a “baby moon,” which would mean it is growing. If this theory is correct, it will be a great tool to use with elementary school students. Michele led a discussion about why we could see the sun and the moon at the same time. Students chimed in saying that it had to do with the earths tilt, and that we see things differently in different seasons. They seemed to have some understanding that things change over the course of the year, but their descriptions seem pretty vague at this point.

I got to introduce the next activity. We further investigated the phenomena of pinhole cameras by doing an experiment on the roof. Each group had a sheet with a hole in the middle (the pinhole camera) that they held in their hands. On the ground, there was a wooden platform, a ruler, and a meter stick. Holding the pinhole camera up allowed the sun (or light source) to shine through. An image of the sun was portrayed onto the wooden board. Students held their pinhole cameras one-hundred centimeters away from the image, and then measured the diameter of the image. In this case, the image was one centimeter wide. Students also tested out what would happen if they held their pinhole cameras at fifty centimeters away from the image. They found that the diameter of the image was .5 centimeters. This demonstrated a solid relationship between the “distance” the pinhole camera was from the image and the “width” (or diameter) of the image.

Back inside the classroom, students were asked to interpret the relationship they found between distance and width. “How can this relationship be explained? Think back to our powerful ideas about light and the phenomena that occurred when we used pinhole cameras during Class 2.” Students began to discuss their ideas with one another. We gave them a task, “If we know that the distance between the earth and the sun is roughly 100,000,000 miles, what is the diameter of the sun?” At first, students had a hard time discerning how they were going to figure this out. Soon enough, they began drawing pictures of how the light was traveling (in straight lines through the pinhole). They used powerful ideas, written words, physical motions, and detailed diagrams to explain how they could figure this out. In different ways, students all came to the conclusion that the sun's diameter was approximately one million miles across. A couple of the groups used a mathematical equation to show the relationship between distance and width (d/w =D/W). Other groups simply stated that the distance between the pinhole and the image was one hundred times greater than the width of the image, so the distance between the earth and the sun must be one hundred times greater than the width of the object or sun. Each group presented their findings.

Several times during the course of the class period, Adam had been selecting random students to go outside with him and record a dot at the end of their sun plots. At short intervals, it is much easier to see how the shadows change. We noticed that the closer it got to noon, the less distance the end of the shadow moved. Students then began their Ning Websites today. In their groups, they uploaded all of the pictures they had been taking over the course of the first three classes onto the internet. There were pictures of their light and shadow experiments, of their shadows outside, and of their pinhole cameras. They are going to be keeping detailed blogs about what they are learning in Physics 111 to use for future reference just like the instructors are doing. The students will be able to refer to them when studying for midterms or when they want to remember what they did and how their learning processes grew over the course of the term. Ning will be an excellent tool for these and many other reasons.

The class as a whole is getting much better about speaking up and sharing their thoughts and opinions with the rest of the students. Talking through their thought processes is very important and being able to present information to others is also very important. Not only are students expanding their ideas about incorporating science and literacy together, but they are also improving their communication skills.

##### Views
• `<a href="mailto:vanzeee@science.oregonstate.edu">Contact Us</a>`