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The CBL

The CBL. Jason Waskiewicz. A Definition. CBL is a Calculator Based Laboratory CBL provides the capability to collect real-world data on the Graphing Calculator CBL is currently in its second incarnation as the CBL2 (shown). What Does it Do?.

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The CBL

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  1. The CBL Jason Waskiewicz

  2. A Definition • CBL is a Calculator Based Laboratory • CBL provides the capability to collect real-world data on the Graphing Calculator • CBL is currently in its second incarnation as the CBL2 (shown)

  3. What Does it Do? • The CBL provides an interface between the graphing calculator and various electronic sensors • Allows rapid input of real-world data • Provides various data analysis features

  4. Why the CBL? • Much less expensive than computers; more portable • Allows students to spend less time on data collection and more on data analysis • Puts computer power in the hands of each student Motion Detector

  5. The Basic CBL2 Package Temperature Probe • CBL2 • Link Cable • Cradle • Light Probe • Temperature Probe • Voltage Probe Voltage Probe Light Sensor

  6. Other Probes • Motion Detector • pH • Photogate • Colorimeter • Several types of force probes • EKG • For a complete list, visit the Vernier Website at http://www.vernier.com pH Probe Colorimeter

  7. Example Lab (from 11-12 Physics) • Students walk toward the motion detector at a constant velocity • Students repeat at several speeds • Students repeat the entire process by walking away from the motion detector • Data can be saved for analysis later in the classroom

  8. Screen Shots of Motion Graphs (moving to detector) Slow Fast

  9. Screen Shots of Motion Graphs (moving away) Slow Fast

  10. Students have already studied distance-time graphs They know that going toward motion detector means a negative slope on a distance-time graph Going away means a positive slope Students are somewhat familiar with the “uneven” nature of these graphs Students first discover how these graphs show whether they are going away or toward the motion detector Students then discover how these graphs can be used to show how fast they were going Students also learn that “real world” data does not give the same type of graph as the book Study of the Velocity-Time Graphs

  11. Study of the Distance-time Graph • Goal is to derive the equation d2=vt+d1 • Students identify the best curve to serve as a model • Students then use the data analysis feature to find the best fit • The picture shows results for the Going Away Slow Situation

  12. Data collection takes the same amount of time With tape timers, students must measure the distance between every pair of dots With tape timers, students would have to first know the equation for velocity (my method allows them to derive it, with some Algebra) With tape timers, students would need to calculate velocity for each pair of dots At least 1 full period of class time is saved by using the motion detectors per lab Motion detectors allow students to compare more situations without extraneous work Why Is This Better than the Tape Timers?

  13. Time must be taken to show students how to use it Cost is greater than other equipment Easier for students to make mistakes in operating the equipment Unexpected problems Takes away some visualization (for example, tape timers show that the dots get further apart with greater speed) Less practice with measurement from scales (rulers, thermometers) Can tempt teachers not to teach traditional data analysis skills Drawbacks to the CBL

  14. My Opinion For 4 years, I have taught science with traditional tools only. This is the first year I had the CBL. I mentioned some of the drawbacks on the previous slides and they all came from personal experience. With the CBL, it is vital to try out the labs under the exact conditions that the students will be working under. I did one on carpet and it worked perfectly. When I took students to the gym to do it, results were nonsensical. The sound waves from the motion detector were bouncing off the hard floor and skewing results. The CBL does, however, enable students to analyze data. For example, kinematics graphs are learned well with the CBL. With more traditional methods, students spend too long measuring dots and using formulas. By the time they get to the graph, the connection between the physical situation and the graph is gone. The CBL makes it clear with the press of a button. In the end, we need to decide what we’re trying to teach. Sometimes the CBL teaches it better. Other times, more traditional methods teach it better.

  15. Resources • Haber-Schaim, Uri, John H. Dodge, Robert Gardner, Edward A. Shore. PSSC Physics Laboratory Guide. Kendall/Hunt Publishing Company, 1990. • ______. Inquiry and the National Science Education Standards. National Research Council, 2000. • ______. Blueprints for Reform: Science, Mathematics, and Technology Education. American Association for the Advancement of Science Project 2061, 1998. • http://education.ti.com • http://www.vernier.com

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