Home PublicationsL&LIssuesVolume 26 (1998-1999) February (No. 5)

	Blowin’ Hot and Cold About My Data
	By Bob Albrecht and George Firedrake   If you've been reading the standards written by the National Council of Teachers of Mathematics (NCTM) and the National Science Teachers Association (NSTA), then you know that both sets encourage student investigations to acquire, graph, analyze, model, and write about real-world data. Yes, the times they are a-changin’—and in a good way.

The times they are a-changin’.

—Bob Dylan

Regular readers of this column know that we’ve been talking about data grabbers. These handy instruments capture physical data in electronic form for analysis in graphing calculators and computers. In the September and November 1998 issues, we described Calculator-Based Laboratories (CBL), microcomputer-based laboratories (MBL), and data loggers. To learn more about them, visit the Web sites shown in Table 1. You’ll find a cornucopia of resources, including lots of instructional materials.

Table 1. Data Grabber Companies, Products, and Web Sites

Just How Hot or Cold Is It?

What is the most-measured physical quantity? We read somewhere that it’s temperature, and that seems reasonable. Temperature measurement and control gadgets are here, there, everywhere. For example, home temperature-measurement and -control instruments include thermometers, heating and cooling thermostats, refrigerator thermostats, stove and oven thermostats, et cetera, et cetera. Temperature-measurement and -control widgets are also in your car. You can view at least one of these on your car’s instrument panel.

Temperature in your area of residence is continually measured and reported in the newspaper and on radio and television. You may use this information to plan activities and events.

Everyone knows about temperature, so it’s a good place to start in introducing students to data grabbers. A temperature sensor is standard equipment in calculator- and computer-based data grabbers, and it’s usually included in the starter packages from the companies in Table 1. A CBL, MBL, or data logger with a temperature sensor opens the door to a multitude of cool experiments. Hot, cold, and warm experiments, too. To find descriptions of temperature experiments, we went to AltaVista (http://altavista.digital.com) and looked for MBL experiments by using this search key:

+temperature +experiment +MBL

 Right away we learned that MBL can also mean “marine boundary layer.” Of the more than 250 hits, most were that kind of MBL. We added “+microcomputer” to the search key and tried again, but we didn’t find anything we really liked. Next we looked for CBL temperature experiments using this search key:

 +temperature +experiment +CBL

Jackpot! We received almost 400 hits with lots of the right stuff. We bookmarked more sites than we can mention here, but we’ll share a few that you may enjoy. Below each site name and address is a brief description snipped from the site, our comments about the site, or both.

“How Fast Can You Cool It?” The instructor guide for this ACEPT Faculty Workshop experiment is available at http://acept.la.asu.edu/products/summer97/mods/exp8/
Exp8instruct.html. According to the Web site, “In this experiment students explore how the cooling rates of objects depend on the surface area and volume of an object. Clay spheres of different sizes are immersed in ice water, while their temperature vs. time data are collected by a temperature probe attached to a TI-83/CBL. Students then compare the cooling rates they measure for objects of different sizes.”

“Your Mother Told You to Never Do This!” This experiment from Pearce Physics is available at http://www.richardson.k12.tx.us/schools/phs/staff/academ/physics/honors/bulbtemp.html. According to the Web site, “Yes, we really stuck a 15-watt bulb into a Styrofoam cup full of water, and we plugged it in. . . . Of course the idea . . . seems a bit crazy, but measurements indicate that even if the water level rises over the base (but not into the outlet itself), the potential of the water remains perfectly safe.”

If you want to do this experiment more safely than the way Pearce Physics does, then you can use a heating element that has been designed for water immersion. They’re available at home supply and hardware stores.

“Shivering Isn’t Enough: Heat Conservation in Homeotherms.” This site by Access Excellence (www.gene.com/ae/21st/TE/PW/EXP/HEAT/tch.html) describes experiments that use standard lab equipment and a CBL to simulate heat loss in “naked” and “insulated” animals and to compare such losses as functions of differences in shape.

“Spreadsheets Using the TI Calculator and CBL.” This student report on a standard type of cooling experiment can be found at http://jwilson.coe.uga.edu/EMT668/EMT668.Folders.F97/Norton/Anderson.html. The students measured water cooling every minute for 30 minutes and then graphed the data and fit linear, quadratic, and exponential functions to it. The site includes graphs, equations, and a set of data you can use to replicate the students’ work.

“Temperature Experiments.” This middle school experiment by C. B. Atlas Animations can be found at www.baylink.org/lessons/3fr_temp-exp.html. The experiment has three objectives: (1) Investigate cooling rates of shallow and deep water, (2) analyze Chesapeake Bay temperature information, and (3) interpret effects of temperature variations on living organisms.

The description lists standards that the experiment is designed to meet, including that students will run the investigations, learn and appreciate that the organisms of an ecosystem depend on one another and the nonliving elements of environment, determine how organisms adapt to a biome’s biotic and abiotic factors, and study and appreciate temperature scales, heat, and heat transfer.

Newton’s Law of Cooling: The Experiment

In addition to inventing calculus and creating the theoretical foundation for most of physics, Sir Isaac Newton developed a model of cooling that is standard in physical science courses. If you are not acquainted with this experiment, then crank up AltaVista and use this search key:

+temperature +experiment +CBL +Newton

 For a short description of the experiment, go directly to “Cooling” at www.ti.com/calc/docs/act/stan4.htm. A complete description of the experiment setup is included there. Students fill a cup with boiling water and use a probe to measure temperature for approximately one minute. They then remove the probe and let it cool to room temperature, measure and plot data, and ultimately see an exponential graph of cooling.

Longer and more-detailed descriptions of Newton’s Law of Cooling, including theory and math, can be found at www.southwestern.edu/~richards/cool.html and www.swin.edu.au/maths/tcubed/tasks/cooltemp.htm. The second site contains an easy-to-follow procedure for doing the experiment with the CBL and a TI-83; it also includes images of the TI-83’s screen and graphs of the data.

The Right Tool for the Task

A temperature experiment might run anywhere from a few minutes to more than a month. However long it runs, an experiment ties up certain resources, so it’s wise to choose the right combinations and types of equipment. Table 2, for example, shows four options and the typical costs of the equipment involved.

Table 2. Typical Costs of Equipment in Use While Grabbing Data

Now we’ll describe some experiments and mumble a few words about appropriate technology for each one.

Body Temperature. Hold the temperature sensor between your thumb and finger or tape it somewhere to your body. Measure and graph body temperature in real time as the data is collected. This experiment will last only a few minutes, so use an MBL, CBL, or a data logger attached to a computer.

Newton’s Law of Cooling: A Short-Duration Experiment. Put the temperature sensor in boiling water, then remove it, shake off the water, and grab temperature data as the sensor cools to room temperature. Graph the data as it is collected. In another experiment of this type, tape a small square of aluminum foil to the temperature sensor, heat it with a hair dryer, and collect data as the aluminum foil and enclosed sensor cool toward room temperature. These experiments can be done in a few minutes, so use an MBL, CBL, or a data logger attached to a computer. After doing short-duration experiments such as these, try longer-duration experiments to learn more about Newton’s Law of Cooling.

Newton’s Law of Cooling: A Long-Duration Experiment. Boil water in a container, remove the container and water from the heat source, and collect temperature data until the water reaches room temperature. This experiment may run an hour or longer, so we suggest using a CBL or a data logger that is not attached to a computer.

Newton’s Law of Cooling: Longer-Duration Experiments. Boil water, pour it into a thermal cup, and collect temperature data until the water reaches room temperature. Our 340-milliliter thermal cup from Recreational Equipment, Inc., keeps our tea warm for hours, so a freestanding data logger is definitely the right stuff for grabbing this data. Start this experiment in the morning, connect the data logger to the computer to “launch” it (a minute or two), disconnect it, and run the experiment. In the afternoon, connect the data logger to the computer, download the temperature data, and then graph, analyze, model, and write about it.

You and your students can invent even longer duration experiments where hot things cool down and cool things warm up. For example, how effective is an inexpensive Styrofoam cooler bought at a grocery store for two or three dollars? Put a six-pack of cold drinks and a data logger in one of these coolers and grab data. Or put a six-pack and some ice in a cooler and collect data. Can these inexpensive coolers really keep your drinks cool for an afternoon at the beach? You can also run this experiment using more expensive coolers.

Camp Stove Boiling Time. How long does it take to boil a liter of water with a camp stove that uses white gas, kerosene, butane, or some other type of fuel?

Boiling times range from three to six minutes, so you can easily run this experiment in an old-fashioned 48.7-minute class period. Use an MBL, CBL, or a data logger connected to a computer to capture the data. If you graph it in real time as the temperature rises from room temperature to 100 degrees Celsius, you’ll know exactly how long it takes.

Think of this as a Consumer Reports type of experiment. You are checking an advertising claim. How do you get the camp stoves? Ask your students if they have them. A local camping goods supplier may rent camping equipment; if so, ask the company to loan stoves for a day. Write creative proposals to companies that make camp stoves.

Do You Trust Your Sleeping Bag? Expose your sleeping bag to the cruel, cold world and collect temperature data inside and outside the bag for a few days. A data logger not connected to a computer is the right tool for this task. You can attach two temperature sensors, one inside the bag and the other outside. As the temperature rises and falls during the experiment, you’ll capture some beautiful wavy data, similar to the sine and cosine waves studied in trigonometry. The temperature inside the bag may “lag behind” the outside temperature and have a smaller amplitude (maximum and minimum temperature).

Grab Data in Your Environment. Collect data in or around or outside your home for several days. A data logger with temperature, relative humidity, and light sensors is great for this task. You’ll get some nice wavy data as the relative humidity temperature goes up and down while the temperature goes down and up. Try fitting a periodic function such as sine or cosine to the temperature and relative humidity data. They may be 180 degrees out of phase (relative humidity decreases while temperature increases, and vice versa).

Have you ever wondered about the true identity of the two authors who speak to you as “we” in the Power Tools column? Bob Albrecht (DragonFun@aol.com) is a writer and developer of science, math, and technology curricula. George Firedrake is his alter ego and takes the form of a dragon. Laran Stardrake, whose quotes sometimes lead off the column, is another of Bob’s “accomplices.” She’s half dragon and half human. As Laran is fond of saying, “Reality expands to fill the available fantasies.” Image from an original painting by Marcy Kier-Hawthorne.

Copyright © 1999, ISTE (International Society for Technology in Education). All rights reserved.