Using Sensors and Models to Answer Discovery Questions

By Carolyn Staudt and Stephen Bannasch

Science is a social construction of knowledge and practices based on observation, analysis, modeling, experimentation, and theorizing about the physical world around us. The National Science Education Standards states, "From the earliest grades, students should experience science in a form that engages them in the active construction of ideas and explanations that enhance their opportunities to develop the abilities of doing science." Too often, however, science is treated only cursorily, if at all, in elementary grades and in a passive format: reading from a textbook. But even very young students can do much more, particularly when the science classroom includes probes and models. And that's just what the Technology Enhanced Elementary and Middle School Science (TEEMSS2) project has been doing: designing activities with probes and models for students in grades 3-8.

In the Classroom: Temperature and Heat

Asked to study an event in which temperature changes and to think about how the changes relate to the flow of energy, fifth-grade students took temperature sensors and interfaces home from school for the weekend. Some compared the temperature of their dog's mouth to their sibling's mouth. Others compared the temperature of the sidewalk to the grass beside it. One young man tested the temperature under the covers of his bed throughout the night. His question was, "Why is it so much warmer when I wake up than when I first crawl into bed?"

Figure 1: Two runs of a NetLogo model with a heater on the left in contact with a block that has different thermal conductivities. Color indicates temperature

He started the temperature sensor and tucked it under his blankets as he went to bed. Throughout the night, the interface recorded the temperature; when he woke, he had a graphical and tabular representation of the data. The graph showed an increase of temperature from the time he laid his head on the pillow to the time he woke. Questions surfaced as he reported to the class. Was the change in temperature due to the blankets? What was the temperature in the bedroom? Did it get colder as the night went on? Did he really become hotter throughout the night or did he just feel warmer?

The class discussion of his and other experiments produced a complex dialogue. The teacher guided the students to frame their new questions in forms that could be answered by further experiments. After collecting more data from numerous experiments, class discussions grew richer and more nuanced as brittle models of temperature and energy gave way to more robust models.

For instance, a commonly identified misconception regarding heat and temperature is based on the fact that a metal object at room temperature feels cooler than a wooden object, which in turn feels cooler than a foam object. The cognitive dissonance of a student’s experience of temperature differences and the "scientific" explanation that the objects are the same (room) temperature can lead to a student developing separate categories of "science" and "real" knowledge. A NetLogo model demonstrates this.

The block on the left (see Figure 1) is a simple model of a finger, which is both warm and generating heat. Students can change the thermal conductivities of the blocks with which the finger is in contact and indirectly investigate the flow of heat by looking at the temperature gradients that develop over time.

After viewing the model, students used a fast-response temperature probe to investigate the temperature of their own fingers, and discovered a wide range of finger temperatures among members in their class. Finally, students held the very small temperature probes between their fingers and three different blocks: aluminum, wood, and foam.

Figure 2: Results of students touching blocks made from three different materials (skin temperature vs. time).

By collecting temperature data with a probe, students were able to easily see why the metal block felt colder (see Figure 2). The temperature data validated their experience. Indeed, their fingers did get colder touching the metal block. The aluminum block conducted heat away from their fingers much faster than the wood or foam blocks. In our NetLogo model the finger is modeled as a perfect heater with infinite thermal conductivity and mass. An improvement would be to model the finger with a finite thermal mass, specific conductivity, and a limited amount of heat input. This would allow the model to simulate the cooling and warming at the skin surface. However, using even our simple NetLogo model and the experiments with sensors, students learn that their bodies are heat engines and that heat flows faster through some materials than others.

Creating Your Own Probeware Activities

In addition to TEEMSS2 curriculum activities we created for three grade levels (3-4, 5-6, and 7-8) in five content strands, we adapted the technology so anybody can make and publish their own probeware activities (see "Do It Yourself" sidebar). The software is compatible with Mac OS X, Windows, and Linux computers, and with sensors and interfaces from five different companies. With a simple user interface -- it's as easy as filling out a form -- the power of probeware is at your fingertips. You and your students can answer your own discovery questions.

Carolyn Staudt is Director of the TEEMSS2 and ITSI projects. Stephen Bannasch is Director of Technology.