Research Matters - to the Science
Microcomputer-Based Laboratories in the Science
by Joseph S. Krajcik, University of Michigan, Ann
Arbor, MI and John W. Layman, Science Teaching Center
University of Maryland, College Park, MD
One of the most powerful uses of the microcomputer in science
teaching is to have students use it as a laboratory tool to collect
and analyze data. Science educators refer to this use of a
microcomputer as microcomputer-based laboratory (MBL). Using MBL,
students utilize a microcomputer and accompanying probes to collect,
record, and graph data to support the construction of their science
concepts. The term probeware has been applied to describe the probes,
interfacing boxes and software needed to use the microcomputer as a
laboratory tool. Examples of probes used to collect laboratory data
include temperature, motion, force, pH, sound, light and
Microcomputers used as laboratory tools may offer a fundamentally new
way of aiding students' construction of science concepts (Linn,
Songer, Lewis & Sterm, 1991; Mokros and Tinker, 1987). They also
allow students to experience what it is like to do science (Tinker
& Papert, 1989). MBL provides opportunities for asking and
refining questions, making predictions, designing plans and /or
experiments, collecting and analyzing data, debating ideas,
communicating ideas and findings with others, drawing conclusions,
and asking new questions. In addition, the use of the microcomputer
may strengthen students' graphing and problem solving skills (Linn,
Layman, Nachmias 1986). For example, a temperature probe helps
students construct an understanding about temperature and heat energy
by allowing them to monitor the temperature of physical systems.
The capability of MBL to immediately transform data from each
experiment into a graph, the most powerful form of information
presentation, is something that has not been possible in the past.
Students simultaneously watch a graph being plotted as they are
conducting the experiment. Much of the rich information obtained as a
graph and produced during an activity, must surely remain associated
with the graph.
Because the microcomputer does the work of graphing,
microcomputer-based laboratories allow students to focus on analyzing
graphs and science concepts involved in the activity. Quick turn
around time also allows students to perform more experiments in the
amount of time typically allotted for lab; moreover, the flexibility
of the probeware gives students more of an opportunity to plan and
design their own experiments. For instance, quick turn around time
allow students within one class period to test how containers of the
same volume and shape but made from different materials influence the
rate of cooling.
In addition, because students must choose some of the conditions for
the experiment as well as the scales for both axes of the graph, the
power of this tool to help students understand information on a graph
is further increased. Most MBL packages allow students to store the
data and to make printouts of the data and the graphs. The printouts
can be used in class discussions, and/or required for the inclusion
of laboratory reports.
Real-time graphing may be one of the key elements in helping students
construct science concepts and graphing skills because it provides
opportunities for students to connect the production of the graph
with the physical manipulation of the materials. Brasell's (1987)
work indicates that even small delays in graph production of 20-30
minutes hinders students' concept development. Real-time graphing
also provides opportunity for students to modify the initial or
experimental conditions and immediately see the effect of their
modification on the resulting graph.
Microcomputer-based laboratory tools are quick and easy to use and
make repetitions of an experiment, with slight variations each time,
easy to do. This is especially important when students say "What if
we did this instead of that." The ease in which students use the MBL
and the real time graphing feature allows students to immediately act
on their own questions and see results while the idea is fresh in
their minds. MBL activities encourage students to create and answer
their own "What if" questions, rather than just answer questions
supplied with the laboratory manual. According to Mokros and Tinker
(1987), students using probeware "have unprecedented power to
explore, measure, and learn from the environment." An important
outcome of using MBL may be that students spend less time gathering,
and more time interpreting and evaluating the data, allowing for more
activities central to critical thinking, problem solving, and
self-monitoring skills. Hence, students are more willing to
replicate, to evaluate, and improve the experiment.
Table 1 presents a summary of the characteristics of using MBL in the
Because of the interactive nature of microcomputer-based
laboratories and because microcomputer-based laboratories link the
concrete experience of data gathering with a symbolic representation
of real-time, many science educators support the use of MBL to
enhance the learning of science concepts, science process skills,
graphing skills, and problem solving abilities for a broad range of
science students. At this time a growing body of research evidence
exists to support these claims (Linn, et al., 1991; Linn &
Songer, 1988; Nakhleh & Krajcik, 1991; Mokros & Tinker,
Examples of Microcomputer-Based
The teacher plays a pivotal role in creating an atmosphere that
allows students to investigate. Our work (Krajcik & Layman, 1989;
Krajcik, Layman, Starr & Magnusson, 1991) indicates that the
overall effectiveness of MBL will depend upon the teachers'
understanding of how to use the new technology, their personal
knowledge of the concepts involved, and their knowledge of how to
help students link their experiences with the concepts. For instance,
microcomputer-based laboratories provide opportunities for students
to collect real-time data, ask "what if" questions and use electronic
sensors to test their predictions and view the results of these
experiments in various forms like graphs or charts. Research in
classrooms indicates that carrying out this type of instruction is
difficult. Science teachers are more comfortable in lecture and
discussion situations, and tend to stress right answers over
hypothesis generation, prediction, data collection, and analysis
(Tobin, Kahle, & Fraser, 1990). The research also suggests that
the instructional component is central to helping students construct
science concepts. The work of Linn and her colleagues (Linn, et al.,
1991; Linn & Songer, 1988) and Thorton and Sokoloff (1990)
indicates that engaging in making predictions prior to performing an
MBL activity appears to enhance students' concept learning. Moreover,
students need opportunities to compare their results to their
prediction after the experiment is completed and to generate and test
new ideas in light of their conclusions. In the University of
Maryland Middle School Probeware Project (Layman & Krajcik,
1988), we have encouraged middle school science teachers to allow
students to make predictions, compare their predictions with the
results they have obtained and ask new "what if" questions based on
the results of their analyses.
MBL is only a tool, and unless researchers have well-integrated
understandings of the science concepts and the processes associated
with the experiments, students will not benefit from the use of these
tools. By providing carefully structured learning experiences,
teachers help students generate new ideas, restructure old ideas and
integrate related ideas.
Students using temperature probes, to collect and graph
temperature data are excellent example of a microcomputer-based
laboratory. A temperature probe attaches to a microcomputer through
an interfacing box and then placed in a chamber of hot water will
produce a graph of temperature versus time and record temperature
history as the water cools.
Figure 1 shows a temperature time graph produced by using a
Examples of laboratory activities that take advantage of this
capability include: a study of the cooling and heating of liquids ,
the influences of a container (insulation) on heating and cooling
rates; and the influence of the volume of a liquid on its cooling
rate. Students can also use an additional feature of MBL, the
influence of transferring heat energy to a system while monitoring
the effect of the systems' temperature, Using a heat pulser, students
control the amount of heat energy placed into liquids, such as water
or glycerine, by changing the number and duration of the pulses (each
pulse with a specified duration places a specific quantity of energy
into a system). By placing the same number of pulses (amount of heat)
into different quantities of water, learners construct an
understanding that temperature and heat energy are two different
Other microcomputer-based tools utilize motion detectors to collect
information about objects in motion, photocells to collect data about
various phenomena that influence light, and sound probes to collect
information on frequency and amplitude. These various
microcomputer-based laboratory tools allow students to explore
concepts in new and exciting ways. One very exciting MBL package for
the biological sciences allows students to attach a miniature
clothespin-like clip to the earlobe or finger that uses a photocell
that senses the pulsations of the blood as it surges through the
tissues. This procedure allows students to collect and graph heart
beats per minute. Using parameters chosen by the student (length of
experiment, collection interval times), data is collected and
A motion detector allows students to produce real-time graphs of
distance, velocity and accelerations for objects moving towards or
away from the motion detector.
Figure 2 shows a distance verses time graph and a velocity graph
that were produced in real-time as a student moved toward and away
from the motion detector.
A motion detector allows students to explore concepts related to
motion in fundamentally different ways than were possible in the
Sound probes allow students to explore sound by comparing, on a graph
generated by the computer, the loudness and frequency of various
sounds. A speaker interfaced with a microphone generates specific
sounds, and the computer converts the electrical signals from the
sounds into visual representations that are projected on the monitor.
As the students hear the sounds, they see a graph of the frequency
and amplitude of the sound waves they are hearing. One example,
always of great interest to students, is a comparison of the graphs
of sounds from two different instruments playing the same note.
Students tell which note comes from which instrument just by
listening, but the question arises, "How else are they different?"
Comparing the graphs of each sound shows that the two sounds have the
same fundamental frequency but different overtones. This possibility
of directly observing a graphical representation of a physical event
as if it is happening may give students a firmer grasp of
Microcomputer-based laboratory packages present many new and
exciting uses of the microcomputer in science teaching that help
students actively construct their science understanding from data
they collect in laboratory settings. MBL tools promote and encourage
students to ask and answer their own "What if questions" and, in so
doing, experience what it is like to do science. However, the
research indicates that MBL tools by themselves will not develop an
environment that will allow students to explore concepts. The teacher
and the instructional setting play a critical role in shaping an
environment that will allow for an active, constructivist
microcomputer-based laboratory setting. Microcomputer-based
laboratories are only tools that must be incorporated into science
teaching by a skillful and knowledgeable teacher.
Brasell, H. (1987). The effect of real-time laboratory graphing on
learning graphic representation of distance and velocity.
Journal of Research in Science Teaching, 24(2),
Krajcik, J. S., & LAyman, J. W. (1989, March). Middle
school teachers' conceptions of heat and temperature: Personal and
teaching knowledge . Paper presented at the 62nd annual
meeting of the National Association for Research in Science
Krajcik, J. S., Layman, J. W., Starr, M. L., & Magnusson, S.
(1991). The development middle school teachers' content
knowledge and pedagogical content knowledge of heat energy and
temperature. Paper presented at the AERA annual meetings.
Nakhleh, M. B., & Krajcik, J. S. (1991, April). The Effect
of level of information as presented by different technologies on
students' understanding of acid, base, and pH concepts . Paper
presented at the 64th Annual Meeting of the National Association for
Research in Science Teaching, WI.
Layman, J. W., & Krajcik, J. S. (1988). University of
Maryland middle school probeware project . National Science
Foundation, TPE-8751744, University of Maryland, College Park,
Linn, M. C., Layman, J. W., & Nachmias, R. (1987). Cognitive
consequences of microcomputer-based laboratories: Graphing skills
development. Contemporary Education Psychology, 12(3)
Linn, M. C. & Songer, N.B. (1988, April). Cognitive
research and instruction: Incorporating technology into science
curriculum. Paper presented at the American Educational
Research Association Meeting, New Orleans, LA.
Linn, M., N. B., Lewis, E. L., & Stern, J. (1991). Using
technology to teach thermodynamics: Achieving integrated
understanding. In D. L. Ferguson (Ed.), Advanced technologies
in the teaching of mathematics and science , Berlin.
Mokros, J. R. (1985). Can microcomputer-based labs improve
children's graphing skills? Paper presented at the MBL
symposium, TERC, Medford, MA.
Mokros, J. R., & Tinker, R. F. (1987). The Impact of
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Thorton, R. K., & Sokoloff, D. R. (1990). Learning motion
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Research Matters - to the Science Teacher
is a publication of NARST