PREPARATION:

This activity works best with students in groups of 3 or less. For a class of 24 students, 12 LABPRO's, calculators and motion detectors are ideal. (LABPRO units cost $179.00, and calculators are approximately $90.00. The motion detector is $65.00. All are available through Vernier Software Company and many other science supply companies.) Make sure that the calculators and LABPRO's have fresh batteries. The batteries last for weeks or months with heavy use if the students are prudent at turning them off after use.

You will have to have about 5 objects per group available. Boxes, cans, etc are suggested, but you can use anything you have in your classroom for your students to use. It is also possible to image a person sitting or laying down with the motion detector as well. The only limitation to working with the motion detector is that you must have the detector a minimum of 0.5 meters above any object. If the distance is smaller than this then your data will be noisy.

*** The graphs that the students generate on their calculators/computers will be upside down relative to the objects. This occurs because the graph produced is Distance versus Time. The taller the object, the closer that it is to the motion detector. You can remedy this in one of two ways. 1. Simply explain to the students the idiosyncrasy of this graphing method and have them transpose their graphs 180 degrees when they draw them in their reports. 2. Have the students come up with a mathematical solution to get the data in the correct orientation. Both methods work well with the data. Choose which method works best for your class.

This activity can be conducted in two parts. The first part is student driven. It will give them an opportunity to test their problem solving and analysis skills. If you choose to do the final part of the activity you will need to prepare an "unknown seafloor". At the end of the student procedure, they are told that they need to check with the teacher to complete the activity. You will have to construct a "seafloor" just as the students had, but yours should be placed behind a screen of cardboard or a sheet draped over some ring stands. Students will use the motion detector just as they did during the first part of the activity, but the only way that they can "see" your seafloor is through their data.

Materials

  • LABPRO System (you will need 1 per group of two. Three students maximum)
  • Meter stick (1 per group)
  • TI Graphing Calculator or Computer (you will need one per group.)
  • Masking tape (for marking their start and end points and to aid in securing string)
  • Bottles, Cans, Boxes, etc. (serve as the objects imaged on the seafloor)
  • Stools (2 per group)
  • String (2 meters per group)
  • Vernier Motion Detector (1 per group)

Time Frame

With introduction, prelab, lab and postlab, this activity works very well as a 3-day lesson with 50-minute class periods. This gives you and your students 1 full period to explore the science background and to become familiar with the setup of the activity and the idesyncracies of the equipment. One day is solely for data collection and analysis. The third day may be considered optional, but is an excellent opportunity to discuss the theory of this method of imaging as well as to reinforce the process of science and data collection.