Probes and Problem Solving

We provide a brief introduction to using probes to gather data in Chapter 3. These devices provide many opportunities for scientific problem-solving and authentic explorations.

Data collection devices all consist of at least two components; a sensor sensitive to some aspect of the physical environment and an interface which allows the user to tell the sensor what to do, stores data the sensor generates, and transfers data to a computer or calculator for analysis. When the sensor can be connected and disconnected from the interface, it is often called a probe. These two components are present in at least three identifiable types of devices:
- A Microcomputer-Based Laboratory (MBL) provides a link between a computer and the sensor. Different sensors can be connected to the same interface device.
- A Calculator-Based Laboratory (CBL) provides a link between a calculator and the sensor. Different sensors can be connected to the same interface device. Data stored by the calculator can usually also be uploaded to a computer.
- A data logger is a free-standing device containing a sensor, interface, and battery. Because data loggers are designed as an integrated unit, they cannot be adapted by attaching different types of sensors. The data logger is connected to a computer for programming and to upload data.

Having some actual data to consider may help you understand the type of investigations that are possible. We recently had the opportunity to borrow a heart rate monitor from a physical education teacher. The device, which consists of a strap worn around the chest and a data recorder worn like a wrist watch, allows complete freedom of activity. The "wrist watch" component is eventually connected to a computer to download data.

We wanted to conduct an authentic investigation using this equipment. Here is what we came up with. We recently purchased a hot tub (called a spa in some locations) and in reading the operating instructions noted some health warnings. Individuals with certain medical conditions are cautioned against using the hot tub. The heart rate monitor seemed a possible way to measure the stress generated by sitting in 104 degree water. The design of our experiment was simple - establish a 20 minute baseline, sit in the hot tub for 20 minutes, and conclude with another 20 minute "cooling off" period. The data generated clearly demonstrates the stress heat imposes on the body. Note the two marks on the X axis. These marks indicate the transitions between stages of our experiment. The middle segment of the graph, the time during which Mark was in the hot water, demonstrates an elevated and accelerating heart rate. Note irregularities in the data appearing near the transitions between stages of the experiment. During these transitions, Mark was in his swimming suit working to first remove and then reattach the hot tub cover with an air temperature of 20 degrees.

Information about Data Loggers, Calculator-B

ased Laboratories (CBLs), Microcomputer-Based Laboratories (MBLs) and probes than attach to the CBLs and MBLs can be located on the Internet. Some of these sites also sell curriculum materials related to these products. Some sources follow.

HOBO data loggers are available from Onset Computer Corporation. (http://www.onsetcomp.com).

The Polar Heart Rate Monitor is available from Heartmind Heart Rate Monitors. Software associated with this product is available for both the Macintosh and Windows operating systems. (http://www.polarusa.com/).

Vernier sells sensors, kits of sensors suited to particular math and science courses, and lab manuals describing a variety of experiments that can be performed with the sensors. The Vernier site also identifies more companies which can use these probes and this information may be useful in extending the small list we can provide here (http://www.vernier.com).

ImagiWorks sells a product called ImagiLab which is designed to work with the Palm Pilot (need web address) and various probes. The Palm Pilot is a hand-held device called a Personal Data Assistant (PDA). A PDA is a simple computer. The data from the Palm can be sent to either a Windows or Mac platform computer for further analysis. ImagiProbe for Macintosh enables students to easily share data in real time over the Internet. Software that comes with the Palm interface allows annotations and sketches to be stored. ImagiWorks makes available suggested activities to get teachers started. (http://www.imagiworks.com)

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