Today's lesson is a bit unusual in that I need to stay home with a child who is ill. I send in some plans to share with students in an attempt to keep us moving on the right track. Despite my absence, I expect students to collect data at their acceleration stations, striving to meet a goal of 1.00 m/sec2. As this is the third day of this effort, I am optimistic at the prospect of their success.
While we are not explicitly analyzing forces, this activity builds a foundation for truly understanding Newton's Second Law of Motion, captured in the NGSS Performance Expectation HS-PS2-1. Indeed, by providing a target acceleration of 1.00 m/sec2, students need to adjust the elements of their stations to hone in on that target. This means, naturally, changing the force acting on the mass. Students implicitly deal with forces in this activity with the explicit discussion of forces and acceleration to follow in an upcoming unit.
As I am home with a sick child today, my substitute shares my lesson plan with my students. They take a few minutes to read it over, then access a link to a 5-minute video. What I present in the video are some hints and tips about using the special data-collection software (Vernier Software) to get high-quality results. There are suggestions about getting good graphs, analyzing those graphs, and transferring the results from the Vernier file format to more accessible formats (Word, Google doc, etc.) for electronic sharing.
Once students have viewed the video, they move to the day's work of collecting data for their lab reports. As this is the third day of our work, they are familiar with the materials and the procedure - today is a good day for high-volume data collection!
Students access the material (ramps, cars, motion sensors, etc.) and return to their task of creating scenarios which result in an acceleration as close to 1.00 m/sec/sec as possible. As part of their lab goals, students are expected to produce an error bar along with their average result. This can happen, of course, only if there is a set of data to review. To that end, students try to quickly hone in on the target value of 1.00 by adjusting their test set-up appropriately. Once they feel as though they are on target, they try to collect a reasonable number of data points with that adjusted apparatus. Typically that means at least seven data points, though students are encouraged to get as many data points as time will allow. I expect that some teams will likely get a dozen or more points, particularly if they are efficient at honing in on the target value.
A second goal for the day is to ensure that each team has at least one high-quality velocity graph to show as a sample in their upcoming reports. Students peel away from their teams to transfer their motion graphs from specialized Vernier Software to more convenient formats (Word or Google docs). Students use flash drives to copy files from the hand-held devices and move to laptops around the room that have the Vernier Software installed. There, they can convert the files for sharing and editing in more common formats.
Students spend the bulk of today's time doing this work. In the final few minutes of class, they return materials to the back of the room and to storage areas, then share any transformed files to myself and teammates.
As a final wrap-up to the day's work, students send images of velocity graphs to me and to their teammates. These images should be used in their upcoming report on acceleration. Indeed, the successful transfer of a high-quality graph from a very specialized format into a common (Word, Google doc, etc.) format serves as a solid indicator of success and readiness for writing. Here's a sample submission from one team:
An important attribute can be seen in the graph above: the slope of the velocity graph is 1.022 m/s/s which is clearly on target of the lab goal of creating scenarios resulting in an acceleration of 1.00 m/s/s.
A second example is shared below, with many of the same characteristics.
Students share these images with one another and with me. Though home with a sick child, I can review these files and assess the day's progress and adjust my next lesson accordingly - a real benefit to a culture of electronic sharing!