Fall 2009 Day 19

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Day 19 Topics

Seasons Dance
Position and Velocity Graphs

Peer Instructor Reflection

Fall 2009: Day 19
Written by: Katie Kizer

We started off class by going into a different room down the hall. Michele did a fun activity to help the students understand why we have different seasons on earth. She asked them what they knew about seasons or the earth and why it has seasons. A couple of students mentioned that we have seasons because of the earth's tilt. A couple of students also mentioned that we have seasons because we are farther away from the sun or closer to the sun. To figure out what ideas were correct, Michele had the students model the sun and the earth during different times of the year.

Michele explained that the earth is always at a 23.5 degree tilt. The students used their bodies to demonstrate the earth's tilt. They moved around the sun (someone standing in the middle of the room) while both rotating and revolving. Through discussion and a lot of question asking, the students came up with a solid idea about why we experience seasons on earth. Depending on the earth's tilt, some parts of the earth are receiving more direct sunlight for longer periods of time than other parts of the earth. As the earth revolves around the sun, the axis remains the same. Therefore, the parts of earth that were getting a lot of direct sunlight during one season, are now getting very little during an opposing season. People living on the equator experience relatively unchanging seasons because they are always receiving relatively the same amount of direct sunlight at all times during the year. Michele showed the class a website after everyone had a concrete understanding. The website demonstrated the earth's tilt, the sun's rays and how direct they were, and how long it appears the sun is up each day. The students had fun wrapping their brains around these new concepts.

During the second half of the class, we explored motion more in depth. For each motion, the students drew a picture of what the graph would look like for position. Then, Emily set up a track in the middle of the room and rolled a basketball down it. She set a motion detector at the top of the track. She had the students try to explain what the graph would look like with both words and a picture based on what they already know about position graphs. The students found this to be a bit of a challenge, but with assistance from the instructors, they were able to correctly draw and describe the position graph for the motion they witnessed. Next, the students explored velocity graphs! They simultaneously watched the position graphs and the velocity graphs change during the same motion. By relating what they already knew about the position graphs, they were able to interpret what was happening with the velocity graphs. They broke each piece of the graph down, and explained what was happening. They discovered that velocity was measuring the speed of the motion. They found: If a change in position is constant, the velocity graph is a straight, flat line. If a change in position is gradual, the velocity graph is inclined. If there is no change in position, the velocity graph remains at zero. The steeper the position graph, the higher the flat line is on the velocity graph.

As with every class, the students wrote down their thought processes and their findings. Then, they spent a few minutes reflecting with their notebook sheets. Everyone learned a lot today. They had a lot to reflect on.

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