Designing Learning Experiences for the Introductory Physics Lab
Dr. Boudreaux facilitates student whiteboard presentations.
Physics has traditionally been taught by presenting concepts and laws in finished form, without much attention to the messy,
creative process that leads to them. Students can take away the impression that, in physics, knowledge springs in whole form from the mind of an expert.
This top-down approach to instruction may unintentionally deprive students of the opportunities for discovery-and subsequent intellectual growth-that come from making
sense for themselves how the world works. Physics can then seem static and inert, rather than the dynamic, human endeavor that physicists understand it to be. The educator
John Gardner has described this common pattern powerfully: "All too often we are giving young people cut flowers when we should be teaching them to grow their own plants."
At Western Washington University, the Department of Physics and Astronomy is working to engage students actively in their own learning by developing an inquiry-based lab curriculum
for the introductory calculus-based physics course. The effort has drawn on a growing body of knowledge from education research about the cognitive processes in learning, as well as
knowledge from physics education research about learning difficulties specific to the discipline.
We are honored and delighted to share our work in this Showcase:
Section I describes our general approach to inquiry-based learning and teaching,
Section II presents the specific pedagogical features of the labs, illustrated with examples
Section III examines student response to the labs and the effects on learning.
A more detailed discussion of implementation, as well as sample lab materials and a syllabus, are included in this Showcase (see "Implementation Notes" and resources in left panel).
I. Overview of inquiry-based instruction
What makes instruction "inquiry-based?" At its heart, inquiry-based instruction involves a shift in focus from the teacher and her presentation to the learner and his thinking.
Traditional physics labs involve verification. Students are presented with an established physical law, and then are closely guided, in a manner similar to a recipe from a cookbook,
through an experiment intended to "prove" the law. This mode implicitly assumes a transmission model for learning. A wealth of research, however, has established constructivism as a
robust model of how people learn (Brown et al., 2000). In the constructivist view, all learning occurs through active mental processes in which the learner connects and integrates what
she already knows with the newly available information. In traditional, transmission-oriented teaching modes, some students, on their own initiative, will actively think through the material
in this manner, but many will not. In contrast, inquiry-based instruction provides explicit opportunities and support for all students to build and validate concepts, laws, and lines
of reasoning for themselves. In designing our labs, we have tried to usher students out of the comfortable but passive mode of receiving knowledge from an authority source. Research in
physics education has shown that actively engaging students in sense-making leads to knowledge that is more useful and more durable (Hake, 1998).
Our introductory physics course, like those at most institutions, does operate within constraints, which to some extent act in opposition to the constructivist-based approach described above.
Subsequent courses and client majors generally expect that a substantial list of concepts, including force, energy, work, momentum, torque, etc. will have "been covered." While open-ended inquiry,
in which students generate their own questions and design and conduct investigations from scratch to answer them, is thus not practical, we do want our students in the limited instructional time available to develop functional
understanding of the content (i.e., the ability to apply ideas, rather than only regurgitate them). To balance the competing demands of breadth of coverage and depth of understanding, we have taken a middle
ground of guided inquiry. Our lab curriculum provides students with clear learning targets and substantial structure while still leaving space for them to construct their own understanding.
Inquiry-based instruction in physics: affordances and challenges. Physicists take pride in the aesthetic and spare logical structure of the discipline. Like chess, or algebra,
a small number of starting assumptions and general laws lead to a vast array of specific results. From the perspective of an expert, very little needs to be memorized; instead,
the focus is on reasoning. Physics teachers can be heard urging their students not to memorize equations, because almost everything "can be derived from first principles." The lab
curriculum at Western emphasizes how we know what we know at least as much as the finalized physical concepts and laws themselves. This disciplinary focus on reasoning lends itself
well to an inquiry-based approach to teaching. While factual knowledge may be successfully transmitted via passive modes of instruction, such as lecture or reading, reasoning competence
comes through active exertion. As the parents of teenagers are well aware, learning the rules of the road can be accomplished through reading and memorizing, while learning how to drive
can only be done by getting behind the wheel!
As part of the cognitive revolution of the mid-20th century, which established constructivism as a model for learning, psychologists, and then physicists, began to investigate
student thinking in detail. Early on, it became clear that physics learners, rather than being blank slates, have their own ideas about concepts and phenomenon, and that these
ideas often lead to non-normative interpretations of what is taught in the classroom. (For studies of alternative conceptions in physics and other sciences, see Driver, 1999.)
Strikingly, the alternative interpretations tend to separate into a small number of identifiable modes or categories, rather than being unique to each individual. For example, when
studying the motion of a coin toss, many students seem to believe that the acceleration at the turnaround is zero (Clement, 1982), a finding that can be characterized as a tendency
to confuse velocity and acceleration. (The velocity of the coin is zero at the turnaround, even though the acceleration is not.) The belief seems to be strongly held - students will
answer in this way even after hearing in class that Earth's gravity provides a uniform, constant acceleration. While the existence of persistent difficulties poses a particular challenge
for physics education, the discipline-specific base of learning research is a resource, allowing teachers to anticipate likely sticking points, and respond with activities that engage
alternative ideas and help students reconcile them with the normative understanding.
Physics students face the daunting challenge of integrating the formal, classroom science being presented with their own everyday sense of how things work. We can regard the latter
body of knowledge as "informal," in that it is practical and generally tacit. Human beings are remarkably adept at constructing this informal knowledge organically through their
life experience. After all, a young child can reliably push a wagon across a bumpy surface with nearly constant speed or propel a ball at just the right angle and speed to hit a target.
Physics education researchers have found that people's everyday ideas about the mechanical world often involve "mini-generalizations" drawn from experience (Hammer, 1996).
While useful for negotiating everyday situations, these rules of thumb can obscure more universal underlying patterns. For example, imagine the child pushing the wagon with steady
speed across the lawn. As soon as the child stops pushing, the wagon quickly comes to rest. From experiences such as this, the child may (consciously or otherwise) form the general
rule ongoing motion requires an ongoing force. This rule makes perfect sense for explaining the motion of the wagon, and many other situations, but can seem to conflict with the formal
statement of Newton's laws, which tell us that an object will continue to move in a straight-line path with constant speed all by itself, and that the role of an unbalanced force is
to change the motion, rather than preserve it. (In forming the rule ongoing motion requires an ongoing force, the child is likely not considering the "invisible" opposing force of friction.)
A primary role of a physics teacher, then, is to design learning experiences through which students become aware of and examine those often unconscious mini-generalizations in light of new,
more systematic observations. Driven by their own curiosity and need for coherence, students can reshape their ideas about how the world works to be consistent with a broader range of
Negotiating the tension of breadth vs depth. Employing inquiry-based instruction can lead to a tension between coverage of material and attention to sense making. Significant time
and a slower pace are required for students to unpack their initial ideas and integrate them with the new formal physics concepts being studied. Creating space for this type of
learning means omitting some topics from the long list in the traditional syllabus. Instructors and students may understandably be anxious about important topics being skipped - especially
in the face of standardized tests, such as the MCAT, that expect knowledge of them. We have found it helpful to maintain continuous focus on differentiating what is taught from what is learned.
It is all too easy to allow the former to substitute for the latter. In the labs, we have chosen to include fewer topics in greater depth, so that students have the opportunity to take full
and confident ownership of the covered content. By experiencing what it means to truly master a concept, students can become more aware of when they do and do not understand, and develop
the ability to ask themselves the questions needed to move their learning forward. In this way, students develop intellectual independence, and become better positioned to guide their own
learning. Inquiry-based instruction can thus help students "learn how to learn."
The role of the instructor. In this guided-inquiry approach to teaching physics, the instructor actively gauges student understanding and responds flexibly to learning needs as they arise.
As she circulates around the room, a teaching assistant or faculty member might stop by a student lab group at work, listening first to assess what the students do and do not understand.
She might follow with questions to draw out student thinking further, helping students to activate knowledge they can use to move forward, to bridge a gap in their reasoning, or to recognize
an inconsistency between a prediction and observation. If a group is struggling, the instructor must judge whether the frustration is a manageable, productive part of the learning process,
or is becoming substantial enough to interfere with the group's work. In the latter situation, which does sometimes occur, the instructor may decide to incorporate some "teaching by telling,"
to confirm productive parts of the group's current thinking and provide encouragement. We have found that teaching in this way requires thorough preparation. In order to respond quickly and
productively, an instructor must be able to make sense of student thinking, which in turn requires a deep knowledge of the physics content itself. Each week, physics faculty and lab teaching
assistants meet to go through the curriculum, discussing the ins and outs of the necessary reasoning and developing possible lines of questioning. Our undergraduate physics majors serve as
TA's in the labs, and their outstanding work is essential to our program.
II. Pedagogical elements of inquiry-based physics labs at WWU
The lab curriculum employs a consistent sequence of instructional activities week-to-week. Students thus know what to expect, and can adjust their learning approaches accordingly.
Table 1 summarizes the sequence.
Elicit initial ideas, engage interest
Before students come to lab
Guided questions and experiments
Build conceptual understanding and lines of reasoning
In collaborative groups during lab
Solidify understanding via metacognitive reflection
In collaborative groups during lab
Activate students' learning on a challenging task with reduced scaffolding
In collaborative groups during lab
Written postlab questions
Practice applying learned concepts to new situations
Written Synthesis Challenge mini-reports
Solidify understanding, develop communication skills
Written learning reflection
Solidify understanding via metacognitive reflection; develop independent learning skills
For more details on the instructional sequencing and specific learning targets, see Implementation Notes.
"Warm-up" questions to surface initial ideas and engage student interest. The seminal volume How People Learn summarized decades of education research by
introducing three key findings, the first of which states that the ideas students bring with them to formal instruction play a major role in what they can
subsequently learn (Bransford et al., 2000). Each week before the scheduled lab period, students complete a written prelab question. These questions, graded
on participation only, are designed to bring student ideas about key physics concepts out into the open, so that students and instructors can examine, modify,
and make use of them. The prelab also serves to operationalize the learning targets, providing a concrete example of what mastery "looks like." Confidently and
thoroughly explaining the prelab is how a learner demonstrates understanding of the learning target to themselves and to their instructor.
The prelab questions involve everyday situations and encourage students to connect the physics concepts they are learning to the real world. For example, in the prelab
for static friction, students are asked to analyze the forces that act on a book when it is held against a vertical wall by a hand pushing sideways. And in the electric
charge prelab, the first in the sequence for electricity and magnetism, students are asked to explain why a sock from the dryer sticks to their pant leg. After working
collaboratively through the guided activities in the lab, students revisit their prelab and have an opportunity to revise their thinking and reflect on their learning.
Guided questions that help students build lines of reasoning. Rather than "turning students loose" in open-ended investigations, the labs define the scope of inquiry by providing
a specific physical context and a sequence of questions to guide students' explorations. The questions serve as stepping stones in a reasoning pathway. For guided steps such as these to be effective, we have found that
careful attention to the spacing of the steps is required. Questions that are too far apart can lose students, while questions too close together can undermine engagement and lead
to answer making at the expense of sense making. See Implementation Notes for specific examples of guiding students through both inductive and deductive reasoning in inquiry-based labs.
A social context for learning. Cognitive science research provides reason to question whether experts in a field are always best suited for teaching novices. In a phenomenon
known as hindsight bias, people tend to attribute unwarranted competence to their own past performance (Kahneman, 2011). This suggests that experts may not always recall the
struggles associated with learning a challenging idea for the first time. The physics labs rely on students to teach one another. The students conduct all of their work in
collaborative groups, and receive frequent prompts such as "Together with you partners, explain how..." and "Through discussion, come to agreement with your partners about..." On
some tasks, the challenge level is such that a group as a whole will often perform more strongly than the strongest individual student. The expectation is for two-fold benefit:
weaker students gain understanding when a peer explains an idea in an accessible way, while stronger students deepen their own learning by having to articulate their understanding
out loud. Collaboration is further encouraged through the framing of the labs and the way credit is assigned, which together work to establish a safe environment in which mistakes
are explicitly valued. (For example, predictions can never be "incorrect.")
Regular formative feedback. The term "assessment" conjures images of unit tests, midterms, and final exams, all of which are used primarily to generate a grade.
Assessment for learning, often referred to as formative assessment, has a distinct purpose: to identify learning needs and guide next steps in instruction. A robust
body of research by Dylan Wiliam, Paul Black, and others has strongly linked formative assessment to learning (Wiliam, 2011). The primary mechanism for formative assessment
in the labs are the discussions between students and instructors. TA's listen and ask questions first, to gauge where students are in their learning, so that feedback can be
tailored to the specific needs of the students. To learn more about how formative assessments are implement in the physics labs, see the Implementation Notes.
Opportunities for students to generalize their results and connect to a "bigger picture." We have found that guiding students through a challenging line of reasoning is not
always sufficient for them to truly take ownership of the concepts involved. To help students make their knowledge "active," in the sense of being able to apply it to new
situations, the labs have frequent prompts for students to discuss the range of
conditions under which a finding applies, or to articulate in their own words the "general rule"
that a specific investigation has led to. When exploring Newton's 3rd law, for example, students use two carts mounted with sensors to measure and compare the interaction forces.
Through guided questions, the lab first directs students to try a variety of specific cases: a symmetric collision in which the two carts approach one other at equal speeds, a collision
in which one cart is initially stationary, and a collision in which one cart has greater mass than the other. Students are then invited to think of and try other situations in which the
interaction forces might have different magnitudes. Finally, the lab prompts students to generalize, asking "Under what conditions are a pair of interaction forces equal in magnitude and
opposite in direction?"
Another opportunity for students to take ownership of their new knowledge comes in the Synthesis Challenge. This culminating lab activity is more quantitative and more open-ended,
involving the concepts developed in the guided inquiry portion of the lab, but with the scaffolding removed. Students must use theoretical knowledge to either build an apparatus
that works correctly on the first try or to measure an unknown value. For example, in the lab on acceleration, after students are guided to interpret and coordinate graphical,
algebraic, and natural language representations of motion, the synthesis challenge asks students to measure the acceleration of a rubber ball during its bounce from the floor.
Students must decide what data to collect and how to collect it, as well as how to analyze that data. When students arrive at a result (typically around 10 g's), they are often
surprised and delighted to find that the value is larger than large accelerations they have heard of before (i.e., that of a jet pilot or astronaut). As homework, students write
a one page "mini-report" about their synthesis challenge. The main grading criterion is that the report is explicit and clear enough that another lab group could repeat the experiment
and verify the conclusion.
Closure and confirmation of student learning. Inquiry-based physics learning is new for many students, and may be quite different than what they expect a physics lab to be like.
This dissonance can lead to anxiety, in which some students understandably become very concerned about knowing what the right answer is. While an ultimate goal is for students
to develop confidence in their own learning, through recognizing what they do and do not understand, we have found it valuable to provide some confirmation of the target learning
after students have had opportunities to build their own understanding. In the Newton's 3rd law lab, after students generalize the conditions in which two interaction forces are
equal in magnitude and opposite in direction, the lab provides a "mini-lecture" - a paragraph of text that states the 3rd law and emphasizes its extremely general nature:
"Note that Newton's Third Law is quite general: it applies to any pair of objects that are interacting with one another. The objects could be at rest or moving, the same size
or different sizes, purple or white, etc."
We note that this approach to confirming student learning is consistent with the mantra "idea first, name later," advocated by Arnold Arons, an early physics education guru
(Arons, 1990). Arons observed that students, and instructors, often fail to clearly distinguish the name or definition of a concept from its meaning and interpretation.
(For example, simply knowing the definition a = Δv/Δt does not mean a student understands acceleration to be the change in velocity that occurs during each second of the motion.)
Delaying the confirmation of ideas helps keep student attention focused on underlying meaning.
To evaluate our lab curriculum, we have measured both student learning and student attitudes. The Force Concept Inventory (FCI), a standardized test that measures conceptual understanding
of Newtonian mechanics, has been given at the beginning and end of our course. Figure 2 summarizes results from 10 different introductory calculus-based mechanics courses taught at Western,
involving a total of 500 students. The normalized gain < g > reports the pre- to posttest improvement as a fraction of the difference between the pretest score and 100%. Many traditionally
taught physics courses have been measured nationwide, with an average normalized gain of 0.22 (Hake, 1998). We find that gains in all courses measured at WWU exceed this nationally reported
average. We emphasize that these learning gains cannot be attributed solely to students' experiences in the labs, as the students completed both the lecture and lab components of the course.
However, the results shown in Figure 2 involve 5 different lecture instructors, who have a variety of teaching styles and emphasize different aspects of physics understanding.
Some instructors focus on conceptual understanding while others focus on quantitative problem solving; some instructors employ guided inquiry techniques while other use a more
traditional lecture presentation. The uniformly strong learning gains, across all lecture sections and instructors, suggest that the labs, which all students had in common, are
improving students' conceptual understanding of mechanics as measured on the FCI. We have found similar results on a standardized test of concepts in electricity and magnetism,
used as a pre- and posttest for the second quarter of our introductory calculus-based physics sequence.
Figure 2. Results on Force Concept Inventory, administered before and after inquiry-based lab instruction in introductory calculus-based physics at Western Washington University.
Online surveys have been administered at the end of the course to gauge student attitudes toward the labs. These surveys ask students to agree or disagree
with a set of Likert-style statements. Of N=149 students responding on one survey, 75% either agreed or strongly agreed with the statement "The format of the labs,
involving guided questions and experiments, was useful for my learning," while only 11 of the students (8%) disagreed or strongly disagreed. A statement about the role
of the prelab ("The prelab annotation activity was useful; it helped me understand the concepts") had a favorable response rate of 82%, while a statement about the
Synthesis Challenge ("The synthesis challenge lab activity was useful, it helped me learn the concepts and quantitative analysis techniques.") had an 85% favorable response.
Students' open-ended comments indicated a mix of positive and negative views. Many students appreciate the inquiry approach and the opportunities it provides for building their own understanding:
"Being able to jump right into doing the lab without explanations from a TA was really nice. It made us think more about really understanding the concepts."
"I wish the entire class was taught through labs...in the lab we always got answers to all of our questions before we left the room that day."
"[My lab TA] was a very good listener and was able to facilitate learning, without just telling us the answers."
Common concerns were also evident. Many students expressed a desire for the lab and lecture to be more closely coordinated. Some students expressed frustration at the frequent experience
of getting stuck on a challenging task or question while the lab instructor was busy helping other groups. Overall, many student comments suggest an underlying discomfort with the lack
of confirmation of right answers:
"Physics is a challenging subject and exceptionally difficult for a 100 level class. More time needs to be spent explaining the concepts rather than throwing students
to the wolves to figure it out on their own."
We view these concerns as appropriate and understandable reactions to a learning environment that is much different from what students are accustomed to. From the student
point of view, the implicit norms for how a science classroom works have suddenly changed, including a change in where the responsibility for learning rests, from the
instructor to the learner. We hope in our ongoing development of the lab curriculum to improve how the instructional approach is framed for students - helping them to
recognize, understand, and ultimately appreciate the shift from an instructor centered approach to one that focuses on student thinking and learning.
At Western Washington University, students in introductory physics labs build their own understanding of key concepts through a process of inquiry. Student thinking and
ideas are the focus; instructors play a supporting role, teaching by questioning rather than by telling. The lab curriculum emphasizes sense making, rather than error
analysis or verification of physical law, with a goal of engaging students in the intellectual adventure of developing new knowledge of how the world works. While the
learning experience is characterized by active collaboration and hands-on work, we have found that it is also important to attend carefully to the specific instructional
sequence for each topic. The design of these sequences has been informed by research on student learning, and refined through cycles of testing and revision. An inquiry-based
approach to physics teaching differs considerably from traditional methods, and from the initial expectations of some students, and thus does require patience to implement and
tolerance for some bumps along the way. We believe that the opportunities for our students' intellectual growth are an ample and rich reward.
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