Laboratory sessions (or “labs”) provide experiential learning sessions for students outside of the lecture hall. In labs, students work in small teams as they practice and develop procedural skills necessary to explore a phenomenon, conduct experiments, write code, collect data, design and test a prototype, etc.
Labs can teach students the specific skills necessary to conduct and interpret specific types of experiments. But they also can teach them much more—the generalizable scientific skills of collaboration, observation, procedural execution, data collection and interpretation, critical thinking, and the use of data to support or reject hypotheses, to name but a few things.
The Purposes of Lab
Labs can serve a variety of purposes for your course:
- Labs can reinforce, apply, and extend upon concepts introduced in lecture. It should be noted that students often struggle to connect what they do in labs with what they learn in lecture, so you should try to make these connections explicitly and frequently. (Indeed, a recent study that surveyed three universities “found universally and precisely no added value to learning course content from taking the labs as measured by course exam performance.” [Holmes NG. et al., 2017])
- Labs provide students the opportunity to practice and learn experimental techniques and the scientific process. When considering which techniques and skills you want your students to learn, consider which skills would be most important for a student who is about to join your lab.
- Students can explore unanswered questions and generate new knowledge in lab. One well-studied “discovery-based” lab in which students study unknown phenomena is the HHMI-sponsored SEA-PHAGES lab, in which students identify and characterize unknown bacteriophages.
- Labs are great opportunities to help students develop confidence in executing scientific skills and thinking and welcome them into the intellectual environment of science. In this way, labs can help students develop their identities as scientists and engineers, which can help motivate students to join one of the research labs on campus and stick with a challenging concentration.
"Traditional" vs. "Inquiry-Based" Labs
Traditionally, many labs provide students with the motivation and all the procedural steps of the experiment, such that the students are primarily charged with performing the experimental steps, collecting data, and interpreting them.
Alternatively, in “inquiry-based” labs, students are prompted to take more ownership of their project, by choosing a question to study, figuring out the necessary experimental steps themselves, and conducting the experiment to determine whether they answered their intended question. Inquiry-based labs therefore motivate students to learn.
Labs can range from “traditional” to “open-inquiry” depending on what instructors provide the students and what the students are asked to generate themselves, as summarized below:
From Weaver GC, Russell CB, and Wink DJ. “Inquiry-based and research-based laboratory pedagogies in undergraduate science.” Nat Chem Biol. 2008 Oct;4(10):577-80.
In another type of lab exercise, a “discovery-based” lab, the questions the students ask do not have pre-established, known answers. Discovery-based labs are therefore more authentic to the kinds of scientific research that occurs in a real research lab, and can capture the exhilaration of discovery that motivates much of our own research.
Assessing Labs
When determining how to assess your students' work in lab, you might consider the following questions:
- Do you want your students to write up a formal lab report, or do you want them to use their lab experience to answer a set of questions? If writing a lab report is important, then your course should include guidance on this.
- Is it important to you that students arrive at a specific outcome in lab? (For example, is it important that they they synthesize a molecule with a particular melting temperature or if they can solve for the correct value of “g”?) Will you grade based on experimental outcome, or based on a student’s explanation of key concepts and rationale for their results?
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Do you care if students can identify meaningful sources of error (other than “human error” or “poor lab equipment”)?
- If so, one approach is to ask students to compare their lab results with their peers, and to repeat the experiment until their results agree with everyone else in their lab section. A recent paper using this approach (Holmes NG., et al., 2015) found that students who were prompted to keep repeating their experiments until their results agreed with their peers were more critically engaged with the lab experiment and could come up with better reasons why their results did or did not agree with the desired outcome.