Yale Center for Teaching and Learning

In the Science Lab

Why You’re There, Pre-med Students, and Grading vs. Learning

As a lab TF, you are responsible for introducing impressionable undergraduates to the gritty world of experimental science. What this means in practice is that you introduce each experiment and then release the students to pursue the glory of successfully reinventing the wheel.

Lab sections can be great for students because they allow them the opportunity to learn actively, to do something physically. On the other hand, they can be long and tedious—the procedures for a given lab are often written out in detail, giving the impression that each lab is just a recipe to be cooked.

For this reason alone the lab TF can make a huge difference in undergraduate science education, since you’re the one who can make clear to students the often murky or unstated relevance of each experiment. Even better, you have an opportunity to instill in students even more lofty and lasting ideals, and to introduce to them the unique experience of scientific discovery itself: the adrenaline rush that accompanies success, the exquisite thrill of solving mysteries, the perseverance and elbow-grease necessary for real progress. 

The Elephant in the Room

Let’s get it out in the open, shall we? Many of the students enrolled in lab courses are pre-med. For many of these students, their primary aim is to get an A in your course so that they can go to the medical school of their choice. This is not an ignoble goal, but it can be the cause of consternation for student and TF alike. Almost every experienced lab TF has had to navigate complaints about their grading.

Yet pre-med students’ concerns should not be brushed aside as petty hindrances. Yes, the med school admissions process is ruthless and highly competitive. Yes, it can be exhausting to be forever on the defensive with your grading. Yes, it can be frustrating if you perceive that students have no real interest in your course apart from its future inclusion on their transcripts. But turn this into an opportunity! The old “You need to do this to get into a good medical school” routine is, admittedly, often all you need to say to get students to pay attention, but this goes only so far. 

Alternatively, think of all that can happen when you relate the lab to the bigger scientific picture. Stress the importance of learning to ask questions, thinking scientifically, and solving problems. Try to work current scientific findings into your pre-lab presentation. Relate the lab to some aspect of the students’ educational career (“this ties in with that immunobiology class you took last year,” “this will help when you take orgo next year”) or life (“this is why your car tires get worn out,” “this is why new windows keep heat in better than old windows”). All of a sudden those four hours in the lab have a point.

As for the grading issue, well, that’s probably going to stay with us for a while. There are a few things you can do, though. Openly acknowledge to your students that you’re aware grades are a concern and that you’re sympathetic to their plight. Then make your standards and expectations extremely explicit. Stick to them rigorously. Students will be less keen to barter for points if they know why they received the grade they did, and if they know that you’re clear on why you gave them that grade. This doesn’t mean you should coldly rebuff all discussions of grading—students do have genuine questions and a genuine desire to learn! —but clear grading guidelines will help to eliminate many grading annoyances. Remember too that you can always refer a student to the supervising faculty member.

Before the Lab

In consultation with the professor, determine the goal of the lab: is it meant to introduce a new concept or technique, to complement lecture material, or something else entirely? Knowing the goal allows you to explain the purpose of the experiment to students. It may also be helpful to attend some of the lectures that are related to the lab if you feel you’re not familiar enough with the topic.

Make sure you’re familiar with the lab design, experimental techniques, equipment, and reagents. Is the lab manual clear to you? (If it’s not clear to you, then you can bet it won’t be to the students.) If possible, run the entire experiment once in advance of the lab session to make sure there are no design flaws (do the vinegar and baking soda make the volcano erupt properly?) and to identify what steps may prove to be difficult for students.

Arrive early for the lab session itself to make sure that everything is set up properly. Acquaint yourself with the lab storeroom so that you don’t waste time during lab session looking for reagents and glassware.

Keeping Your Students and Yourself Safe in the Lab

It’s difficult to call a lab a “success” if there’s been a horrible accident, so stress safety procedures and policies again and again, both before and during the lab. Enforce them strictly. Prohibit smoking, eating, and drinking; in particular, discourage students from eating chemicals. Check out the first aid kit, (eye) shower, fire extinguisher, and fire blanket. If you’re teaching a lab that involves potentially hazardous chemicals, make sure that the eye bath actually works: many of them haven’t been used in years and may issue forth viscous brown goo into the user’s face. 

Most importantly, know where the phone is and whom to contact in case of emergency. Have the emergency contact’s name and contact information posted prominently in the lab.

Familiarize yourself with the potentially hazardous steps in each experiment. In sum, make sure that your students understand the potential hazards in the lab, adhere to the safety rules, and know what to do in an emergency.

Running a Lab: Expectations and Time Management, the Lab as Learning, and Cleaning Up

Preliminaries

At the first lab, make sure to introduce yourself and discuss bureaucratic matters such as office hours, grading, and other policies. Prepare a handout with all of this clearly outlined so as to save yourself some grief later. Set strict ground rules regarding how and when students may contact you, so that you can create boundaries between your professional life and your personal life.

Determine in advance whether students will be working in groups or individually. If you decide to use pairs or groups, it usually works best to assign lab partners rather than leaving the choice up to the students. This way, you can ensure that everyone has a partner and avoid pairs of chums who use the time to socialize. Keep an eye on the groups to make sure that everyone is contributing to the labor, and don’t hesitate to shuffle students if a partnership isn’t working. Be very clear about how you expect students to work together, and to what extent collaboration is permitted on lab write-ups (e.g., student pairs may use the same data but must write individual reports).

After introducing the lab and discussing safety regulations and precautions, you can move on to explain the experiment and its relation to the class lectures as well as to The Advancement of Science. Present any relevant theories, explain the objective(s), and answer any student questions. This introductory material is vital to the success of the lab: making clear to students the context of the lab and its relevance to the larger scientific picture makes them more likely to learn while they’re measuring things and making observations later. You don’t need to go on forever—in fact, try to avoid the semblance of lecturing—but these few minutes are the best chance you’ll have to encourage big-picture, synthetic thinking during the minutiae of the lab that follows.

Expectations and Time Management

Some students will come to lab totally unprepared, begin the experiment right away, mindlessly follow the instructions, and then go home to write their lab reports. These students are the ones most likely to be safety hazards, but they’re also not getting much learning out of their not-insubstantial time investment. Asking students before each lab to make a flow chart of the experiment is a good way to get them to read it through and think about it beforehand. This will also help students be more efficient in completing the lab.

To the same end, set clear guidelines about when you expect students to have finished the various parts of the experiment, and set a time by which the lab should be completed. Check on student progress regularly (maybe every half hour or so). No one—with the possible exception of necromancers—wants to be in the lab until midnight. Identify the students who usually stay behind and try to diagnose why they struggle; some feedback on their performance and a few pointers on time management and organization might help them to finish faster.

Labs as Learning

Labs entered science education as a way of supplementing and reinforcing the ideas students learn in the classroom, and in the paragraphs above we talked about making that role explicit to your students. No matter how brilliant your introduction, however, few students are likely to pause in the middle of a lab to ask themselves what the blue color in the flask means about the potential chemistry that is occurring. Most are content to marvel at the color and consider the process magic. 

A well-placed, well-conceived question (“Why do you think the flask is blue?”) can jump-start their thinking and turn the attitude of “What’s the next step?” into one of “Neat-o! Why did that happen?” (Students might not be equipped to answer your queries at the beginning of the semester, but that’s okay—you can help them arrive at the right answer with more specific leading questions.) These sorts of questions don’t need to turn into a mini-lecture, but their frequent and constant appearance subtly establishes the lab as a place where doing something leads to learning something.

When you are teaching a laboratory course, downtime is inevitable. Help students use this time productively by implementing some of the following suggestions:

  • Have students get materials and equipment ready for the next steps of the experiment (you’ll probably find that your most efficient students do this without prompting).
  • Discuss a figure or figures from a relevant journal article that will help students practice the types of analyses used in the lab.
  • Talk more about a technique or methodology that students have learned about (i.e., when it was originally developed, how it can be used to learn new information, how it can be optimized for a particular application, etc.), and then provide a sample problem or experiment in which that technique or methodology is used.
  • Brainstorm experiments that could be performed after the day’s experiments are completed. What would be a natural next step in the research?
  • Ask students to do an in-class writing exercise that could involve analyzing or commenting on topics relating to the week’s lab or writing a solution to a group problem (such as, “Describe an approach by which additional genes involved in Process Y could be identified”). Try to design questions that will help students think more like a scientist.
  • Encourage students to take a look at their data and think about how they will write it up. Address common questions about analysis and interpretation before students leave for the day. Consider providing a set of “dummy” data to model what students will need to do on their own.

Students can often arrive at the correct answers to your questions by involving their colleagues in the conversation. Encouraging communication among students (about the experiment!) early in the semester will make them more likely to consult each other if something goes wrong or to discuss differing or unexpected results. This is good news for you, since it’s usually much easier for students to ask the TF their questions, and it’s usually easier for the TF to take the path of least resistance and simply give them an answer rather than helping them figure out the answer on their own. That’s hardly ideal, though. It’s frustrating to answer the same question twenty times in an hour, and it leaves the students no closer to being independent thinkers than when the lab started. On the other hand, requiring that students consult with each other before they approach the TF with a question, or asking a student who is a step ahead to explain the next step to the rest of the class, will increase students’ independence, morale, and communication skills.

Cleaning Up

Emphasize cleanliness during the experiment. It’s not only essential for the safety of the lab, but also for a successful experimental result (just don’t mention the train wreck on your own lab bench). After the lab is finished, make sure that students clean up the bench and other working areas before they leave. Carefully monitor the waste disposal. Mixing biological, radioactive, and normal waste with chemical reagents and sharps is a safety hazard, so everyone in the lab should be responsible for properly disposing each type of waste. If you’re not strict about your cleaning policy, you’ll be cleaning up by yourself.

After the Lab: Lab Reports and Teaching Scientific Writing

It can be a real help to you to have students fill out brief evaluation forms after each class or experiment, either on paper or via email. You might simply ask what the most difficult or confusing part of the experiment was, or what you (as the TF) could have done differently or better. Commenting on the feedback at the start of the next lab will help keep communication open between you and your students. See Chapter 5 for more information on student evaluations.

Lab Reports and Teaching Scientific Writing

Lab reports need not be just a recipe and a short commentary—they are an opportunity to help improve your students’ writing abilities and communication skills. Science is often thought of as the place where good writing goes to die, and many undergraduates therefore assume that they don’t have to pay any attention to the quality of their writing when they take a lab course.

As a lab TF, you’re on the front lines of the battle and have the opportunity to repel the advancing phalanx of these myths. You may even be a TF in one of the WR (writing-intensive) courses offered by the Chemistry, Ecology and Evolutionary Biology, Molecular, Cellular and Developmental Biology, or other departments. But even if not, emphasize that developing scientific writing skills is important for all students taking the class, not only for those who envision a career in science.

Improving students’ scientific writing requires substantial effort on the part of the lab TF, whose comments and feedback are imperative to each student’s progress. This can be frustrating for the TF not only because of the time commitment, but also because students will reap only as much as they sow, and you might often feel that your helpful commentary falls on deaf ears.

The trick is to avoid spending your every waking minute grading lab reports—keep in mind that you’ll have about fifteen to twenty multi-page reports each and every week—while still providing feedback that students can use to improve those reports. Indeed, the difficulty of teaching scientific writing is among the most pressing challenges facing TFs in the sciences, but this is one of those cases in which scientists might learn something from their colleagues in the humanities, who have long been charged with teaching undergraduates how to write.

A few tips:

  • Indicate early on whether reports will be written individually or in groups.
  • Distribute a handout that states clearly what you expect in a lab report. Provide examples of A-level reports, B-level reports, and so on, and explain in detail what is good and bad about each.
  • Be explicit about how you’ll grade reports: state how many points a given section is worth, and what will cause points to be deducted.
  • If it seems necessary, prepare a handout on scientific writing, and bring in publications from journals that illustrate the principles of good writing. If possible, take a few minutes to discuss them together.
  • Likewise for posters: if making one is part of the grade, bring a few in early on for students to admire and keep in mind as they work on their own.
  • Don’t feel obliged to fix every flaw in every lab report, in part because you don’t have the time but also because most students will not be able to fix every flaw in a week’s time. Instead, pick one or two points to focus on. Rewrite one or two sentences, fix the first few its/it’s snafus, correct a glaring omission or misunderstanding. Small steps, baby. Small steps.
  • You might consider giving students the opportunity to rewrite one or two lab reports early in the semester so that they have an immediate opportunity to learn from their mistakes. This can mean more work for you for those few weeks, but probably less than you think, since not everyone will take advantage of the opportunity. Consider too that improved lab reports early on means better lab reports later on. It’s an investment.

In short, you can make the task of grading lab reports a whole lot easier by making expectations clear at the beginning of the semester. And stick to ’em!