Chapter 6: Reconsidering labs & demonstrations for doing model-based inquiry

Chapter 6 Reconsidering labs and demonstrations for model-based inquiry. Don't throw away those owl pellets just yet. The student teacher looked up and caught sight of the clock. The change of classes loomed like an approaching storm. "I'm coming around with a trash can," he said. "Please make sure you throw everything away. I don't want to see any owl pellets left on the desk." The students who had been working attentively, dutifully gathered up the tiny fragments of bone and fur and used a sponge to wipe down the table tops. Watching from the back, it was all I could do to stay in my seat. Rarely had I seen such fantastic teaching in an urban science classroom, particularly with so many English language learners, and it broke my heart to see the lab come to such an ignoble end. It felt as if a world-class chef had prepared a meal in front of me and then tossed most of it into the garbage. This food, however, had already been eaten by an owl. The undigested bits had been regurgitated into pellets and collected by a science supply company from a forest floor somewhere, then wrapped and sold to a high school biology classes around the country. For the past hour, I had watched lab groups open their foil packages and disassemble a lump of material the size and color of a cigar stub. This, students were told, was an owl pellet. The students had slowly dissected their pellets with tweezers and scalpels, finding parts of rodents and various other creatures in them. A key provided by the teacher had helped students keep a running tally on the board of each piece they could identify. Whenever a particular grizzly bit emerged, like a jaw, claw, or feather, all of the students were quickly summoned by the excited group to check it out. Students had been animated by the activity, and even the somewhat squeamish were having a good time. All of this came to a screeching halt at the end of the period. I have a great deal of sympathy for teachers who run out of time in the middle of interesting science classes, especially when they have been judicious by not squandering the beginning of the period on an unnecessary preamble of instructions, warnings, or tangential lectures. Stopping is not such a big deal with dissections or air track collisions. There is no hardship in putting plastic over a frog or just setting aside gliders until the following day. But to anyone who has ever had students heat test tubes with alcohol burners, trace complex circuits to solve an electrical problem, or count populations of fruit flies. Sometimes stopping too soon means needing to start over. There is nothing more frustrating than engaging students in deep and patient work, only to be undermined by the bell. My critique of this alpellate lab was different, however, because even though it was laden with scientific possibility, the students stopped just short of actually doing science. Rather than trying to model an ecosystem or learn something about the environment where these owls lived, the students just took the owl pellets apart, made a list of what was there, and called it a day. They had used some of the tools of science to track their data and explore the scientific idea of a food web, but had not done much more than identified the phenomenon under investigation. As I left the room, it felt as if the students had been led right up to the edge of engaging in genuine scientific inquiry, only to retreat at the final moment. How can we as science teachers rethink situations like these, and take up the challenge of redesigning our labs and activities, so that students are more engaged in actual scientific practice? There is a historical and defining feature of science teaching that seems to cut across all subject areas and grade levels, which may be reduced to the phrase, "Let me show you something." For generations, there were only a few places most people could see a chunk of sodium explode in water. Watch a penny and feather fall together in a vacuum, or witness first-hand observations of microorganisms. Documentary films and television shows were one source of exposure to these experiences, as were museums. But for most young people, studying science in school was the primary method for gaining access to phenomena that lay beyond the reach of their everyday experiences. Those school science necessarily dealt with helping students examine familiar experiences in new ways, teachers, scientists, and curriculum writers made the inclusion of demonstrations central to their work. They designed lessons and materials specifically with the goal of exposing students to phenomena they had not seen previously. The purpose of a well-designed lecture, like those of Michael Faraday at the Royal Society, was to walk learners through an explanation of what they had just seen. The spirit of this pedagogy, which I will call demonstratism here, lives on in school science in the form of lectures, demonstrations, and laboratory experiences, whenever the main purpose of teaching is to expose students to a particular phenomenon or provide a way to think about a particular science idea. And to be fair, things teachers like to show students can be really interesting. For example, I can vividly recall the first time I saw the thermite reaction, rain down molten iron inside a lecture hall. Another demonstration I saw had hundreds of mouse traps in the large glass tank acting as uranium atoms, baited with delicately balanced ping pong balls as neutrons. A single ball was tossed in the tank to start the chain reaction, and this helped me visualize nuclear fission better than anything I had ever read. A key element of demonstratism, which I will critique here, is that the cognitive load placed on the students is often quite minimal. In some cases, just experiencing the phenomenon is considered an end in itself, with very little being asked of the student other than making observations. This explains how students can spend an afternoon taking apart and looking through owl pellets, and only scratch the surface of big disciplinary ideas in ecology. In the pre-internet days of limited access to science knowledge, demonstratism may have been a rational philosophy for science teachers, who had access to knowledge and materials that students did not. In these classrooms, demonstrations, laboratory activities, and curated images and videos served the specific purpose of orienting students to the topic by helping students visualize the phenomenon. Yet, the idea of a right answer, known by the teacher and unknown to the students, lurks just below the surface of this approach. The practice of beginning in class with a discrepant event, what we might call today a puzzling phenomenon, became a commonplace way to engage students' interest by showing them something unexpected. For example, a teacher could rub a balloon on a sweater and then touch it to a fluorescent tube, making it flicker briefly with light. These teachers often perform their demonstrations with a degree of showmanship. Done well, these can hook students' interest and motivate them to want to know the answer to the mystery. But they can also take on the appearance of a magic show, placing the scientific understanding at arm's length, even while kindling students' sense of wonder. In the 21st century, students in our science classes now have less need of all this showing. In my own 20th century chemistry classes, I would place a piece of sodium metal, the size of a lentil in a shielded beaker of water, so my students could see the vigorous reaction on the surface. But now, being able to watch online videos of people lobbing soft ball-sized chunks of sodium into lakes is only a few clicks away. Once upon a time, our students needed our slides and videos to see glaciers calving, slow-motion crash testing of cars, and slime molds reproducing. Now, they can see these things whenever they want, with or without us. The failure of demonstratism is that even as it may serve to motivate students, just seeing or experiencing phenomena in a science class is no longer enough to foster deep science learning, if it ever even was. A panel report from the National Academy of Science states that the purpose of school laboratory experiences is to, quote, "provide opportunities for students to interact directly with the material world, or with data drawn from the material world, using the tools, data collection techniques, models, and theories of science." In science class, the word lab is used as a shorthand for a lot of different activities, and the one commonality that connects them is that they all involve active participation from the students. In lab, students are no longer sitting listening to a lecture or taking notes. They are doing something. There are a lot of different activities that get called lab. And some of them, the tools, data collection techniques, models, and theories of science are quite evident. In one biology class from I visited, students rotated from station to station, peering through microscopes and sketching the microorganisms they observed. When my physics students use air-track gliders to determine the effective force on speed, they were engaging in data collection to generate a conceptual model. Some labs require students to follow a set of procedures in order to arrive at a desired level, like the chemistry lab in which copper dust is heated and accrucible, and changes color and gains mass, and students must figure out why. Other times, labs aim to teach a specific skill, such as how to perform an acid-based titration using burets and an indicator. Many teachers talk about activities as if they were the same as labs, but some of these may lack any connection to scientific practices beyond the topic. Part of the issue is the easy conflation of words used to describe school science laboratory activities. Even if an activity takes place at a science workbench, is hands-on, and is pedagogically valuable, it still might not fit the above definition of a laboratory experience. Plenty of science teachers take advantage of the extra space that a science classroom occasionally affords to spread out, but that does not mean that students are necessarily acting like scientists. Sometimes lab just means taking notes in a different seat. I have seen lots of things called lab, which probably ought not to have been, such as cutting out photocopy chromosomes and gluing them in pairs, crafting jewelry with rocks polished in a tumbler, and making conservation of energy posters. These were hands-on activities, but engaging in them did not necessarily require students to draw upon the practices of science. I had two experiences that started me down the road to rethinking labs. The first was when I was teaching a ninth grade introductory physical science class, and a pair of lab partners had a difficult time getting started. It was a distillation lab in which the students heated a mixture of ethanol and water to find the individual boiling points, and then use that information to separate the liquids using a condensing tube. The two girls had completed their data collection just as the bell rang, and I let them hang back a few minutes to clean up. As we talked, they made it clear that even though they could probably write up the lab report, they now actually understood what they were doing, and said they would really like to try doing the lab over. They were persuasive, and the next day they came in and got right to work in the back of the room. The lab reports they eventually turned in were far above the level of work they had produced for me up to that point. It was clear that doing an entire lab activity more than once had created unforeseen benefits for learning the science. It was also a lot like real science. When I had worked in an organic chemistry lab the previous summer, I often made mistakes that sent me back to square one, but these were productive failures that taught me a great deal about the actual science of what I was doing. They also motivated me because I finally felt like I knew what I was doing, much like my own students in the distillation lab. The repetition of labs became part of my teaching toolkit from then forward. The second moment came in teaching a methods course for future science teachers. When one student got mad on behalf of her younger high school self, "Why does every chemistry lab just end with a white solid?" she asked with visible irritation. She understood the concerns about safety and the cost of materials, as well as the obligation for high school chemistry classes to teach students certain laboratory skills and the use of specific tools. It was the lack of imagination in chemistry teaching and the prescriptive nature of lab experiences in school that bothered her. She felt they were all carefully constrained recipes, even when a procedure allowed for some deviation for inquiry because there was a right answer at the end. And students were often forced to calculate exactly how far away they were from that. I could not disagree. Some labs are actually quite clever in the way they disguise the science as they deliver the pleasure of a right answer. One old physical science study committee, PSSE Lab, comes to mind, where students measure the curvature of an electron beam in a vacuum tube within a solenoid's magnetic field, then perform some calculations to find the mass of an electron. How could someone not feel like a scientist doing something like that? Of course, it was all a setup because as long as students made the original measurements within the correct order of magnitude, within a centimeter, the result they were calculating with the provided formulas would produce an answer of the electron's mass that was reasonably close to the answer they could look up. One physics teacher friend, whose ground vacuum tubes for this activity until the year he retired, gleefully called this a fake lab. I can recall my chemistry lab in high school, and how our teachers always set out the materials we needed, but rarely ventured past the edge of the single desks into the sea of black tables to take note of what we were doing. What we were doing in fact was engaging in inquiry with the dropper bottle of six molar nitric acid. My lab partners and our were fascinated by what would react with it, pennies, lab sink fixtures, our skin, and what would not, the cover of the chemistry textbook. To us at the time, science inquiry meant playing around with random configurations of science materials until something unexpected happened. School science labs, especially in chemistry and physics, were often infused with the notion that one must do them right, which usually meant that nothing unexpected was going to happen. As a student, I was unable to see any form of systematic scientific investigation between random inquiry and cookbook labs as a way to produce knowledge. It was not until graduate school that I realized the depth of this problem and its relation to a common misunderstanding about the nature of science. Long before taking high school classes, I had learned the formula for writing lab reports. They began with a title and purpose, followed by a hypothesis, a list of materials, and a sequential procedure. Only once those steps were completed on composition paper in legible handwriting, where we permitted to proceed with actually doing something. After a while, I decided that it was a way to slow us down, so the fun part of the class was not over too quickly. When I became a teacher, this hypothesis was confirmed. I have since heard this approach referred to as PHEOC, FIAC, which is short for problem, hypothesis, experiment, observation, and conclusion. As a new teacher just trying to survive my first year, I used the same pedagogy uncritically, because I knew it would count as teaching science to passing administrators, even if it made me uneasy. The reason FIAC seemed so attractive, even if I chafed against it both as a student and a teacher, is that it seemed like it was a guaranteed process for producing knowledge. By dutifully following a series of steps, there was a promise of fully formed knowledge popping out at the end. In my ignorance, I thought that scientists just messed around doing random experiments until they made knowledge. And when they did, they turned it into a PHEOCABLE lab for science classrooms. While I still think there's value in keeping good records and writing about what happens in the lab, these days I have a difficult time advocating for the PHEOCABLE edigogy. It seems there are much better ways for teachers to provide opportunities for their students to learn to think scientifically. The best laboratory experiences I have witnessed in science classrooms are the ones in which students are involved in sense-making of some kind, rather than just witnessing the science. In these classrooms, there is a clear demarcation between the acquisition of a skill needed for a lab, like mounting a slide, calibrating a probe, or using glycerin to insert glass tubing into a stopper, and a genuine experiment that helps students reduce the ambiguity in an explanatory model. Teachers in these classrooms leverage the practices of science at just the right time, teaching metric measurement, for example, when it is needed, instead of spending weeks on it at the beginning of the year. These teachers also let students take different pathways, within certain boundaries, in order to ask their own questions and try out their own ideas. Sometimes this means letting go of the belief that every student in the science class needs to be involved in exactly the same learning activities at all times. This one can be tricky, but the results can be glorious. For example, I do not regret letting Jamila investigate the relationship between color and wavelength on an old spec-20 photometer I found in the Ohio School Physics Store Room. I excused her from the assignments that the rest of the class was doing, because she was really adamant about wanting to understand the nature of color. It took her a day and a half to realize that she needed to keep track of her readings in a table, but eventually with some coaching, she learned to be systematic. Her biggest puzzle was why the readings seemed to be the opposite of what she expected. She had thought that the sample of water with blue food coloring would absorb the blue wavelengths, and red would absorb red, but the opposite happened. I remember her aha moment on the fourth day, when she realized that the apparent color of a solution was the result of the wavelengths not being absorbed by the sample. In that moment, it was clear that she was learning like a scientist, posing and investigating her questions within a well-defined problem space. Some science teachers and science education researchers offer a different way of thinking about demonstrations and lab experiences, one more deeply rooted in modern understandings about the way students learn science. This approach, sometimes called model-based inquiry, suggests that all science learning ought to begin with a carefully selected puzzling phenomenon of some kind, and this is where demonstrations can play an important role. The idea is not to just have students figure out the answer, but to develop an explanatory model for the phenomenon. Within this approach, the teacher does not play the part of answer-giver, but rather supports students in developing and revising their models, first eliciting students' ideas about the phenomenon and then supporting their construction of a model. Teachers can also introduce scientific ideas along the way that students can include in their models. By making lab about model development and refinement, teachers can offer explicit opportunities for students to connect their existing ideas to the science. After the owl pellets were all cleaned up, I readied myself to talk with the cooperating teacher and her student teacher. I thought about what I wished had happened. Throughout the lesson, lots of good questions had come up. What kind of food did the owls pray eat? How much energy did the owl need to survive? And how much did it have to eat to get it? What did the remains of the prey reveal about the owl's behavior? What patterns existed in the types and quantities of prey? Why wasn't fur digestible? However, all of these were questions posed by teachers to students who answered as best as they could. I could not help but feel that if the students had been encouraged to formulate and investigate questions about what they were finding, the owl pellet lab might have taken a little longer and looked much different. And instead of regurgitating fragmented bits and pieces, students would have had a much better chance of digesting the big ideas and practices of science.