Indiana University Teaching Handbook
- Preparing Lab Sections
- Managing Laboratory Sections
- Safety Procedures
- Student Preparation
- Supervising the Experiment
Science labs can be among the richest experiences students have at the university. It is one of the few opportunities students will have to practice science much in the way professionals do. Often, though, labs are presented as mere recipes in which students follow precise instructions to arrive at a conclusion whose importance is not clear. In order for labs to be effective, students need to understand not only how to do the experiment, but why the experiment is worth doing, and what purpose it serves for better understanding a concept, relationship, or process.
Preparing Lab Sections
Adapted with permission from University of California Santa Barbara TA Handbook
The most important thing you can do to ensure that your lab sections run smoothly is to be well prepared. Your preparation, prior to the start of the semester, should include being acquainted with the storeroom of the lab so that time wont be lost during a lab looking for necessary equipment or materials, and if applicable, knowing the location of the first aid kit, basic first aid rules, and procedures for getting emergency assistance.
Basic weekly planning for your lab section might include the following.
- Know exactly what the students are supposed to learn and why they have to learn these things. This will come in handy when your students start to wonder why theyre doing what theyre doing.
- Perform the entire experiment in advance. There is no guarantee its going to work as advertised in the lab manual. By going through the lab yourself, youll be familiar with some of the stumbling blocks that your students may confront and youll know the subtler points of the process you are demonstrating. If this isn't possible, at least read through the procedure as though you were doing it. And familiarize yourself with the equipment that your students will be using. Also, obtain some sample data and work the calculations and answer the questions (without using the key).
- Read and study the theory on which the experiment(s) are based. Your understanding of the theoretical aspect of the lab should be useful to you in handling most student questions which dont deal with concrete parts of the experiment(s).
- Research the relevance of the experiment, both the technique being taught and the applications of the theory being demonstrated.
- Talk to experienced instructors. They will often have very useful tips about things you are teaching.
- Decide how to introduce the lab most effectively. Before students start the days lab, will they need you to demonstrate the procedures that theyll be following? Is a handout with written instructions in order? Do you want two students in the class to demonstrate the experiment to the rest of the class? Will a 15-minute lecture about the theory and intent of the lab suffice? What safety information do they need? Your initial introduction to the lab or the days first activity can set the tone and motivation for the rest of the lab.
- Plan how you will guide students in preparing their lab reports.
Managing Laboratory Sections
Adapted with permission from Farris, 1985
Labs are sometimes offered in conjunction with large lecture courses so that students may acquire technical skills and apply concepts and theories presented in lecture. Labs, however, are often stand-alone classes with no connection to a parent course. Even where they are related to another course, they often have their own agenda that may not be related to the lecture. This hands-on experience encourages students to develop a spirit of inquiry and allows them to live for a semester as practicing scientists. It may sound trite, but you really do have an opportunity to help students develop some appreciation of the mysterious scientific method.
You neednt overwhelm them with the Heisenberg Uncertainty Principle on the first day of class, of course. In fact, to realize your full potential as a laboratory instructor youll have to recover some of the neophytes enthusiasm for mastering fundamental principles and techniques of the discipline. Think of yourself as wearing bifocals so that you can examine a problem from the professionals and the students points of view simultaneously.
Safety takes on special importance when you are directly responsible for the health and well being of 25 or more laboratory students. Window shattering explosions are rare, but it is not uncommon for students to break beakers of acid, cut themselves while working with glass tubes, or ignite a stack of lab notes with a Bunsen burner.
Most departments orientations cover safety procedures, but if they do not, the professor or lab coordinator in charge of the course will probably take responsibility for describing departmental policies. Throughout the semester you should demonstrate to students the proper technique of decanting, mixing, and measuring liquids, handling and cleaning glassware, organizing a work area, disposing of hazardous materials, and using burners and other equipmentall of the precautionary measures you perform almost unconsciously; your students, however, dont have your experience and will therefore appreciate your concern and advice.
Those who have only a hazy recollection of Wednesdays lecture will follow directions mindlessly, but those who have reviewed lecture notes and the lab manual will have some understanding of the experiments importance. Devise some means to ensure that students are familiar with the lab before they come to class. Some instructors feel that grades on lab reports are incentive enough, while others require students to perform some pre-lab exercise, such as submitting a statement of purposes and procedures or an explanation of why and how the experiment is relevant to the course. Others invite students to office hours preceding the lab, helping highly motivated students to prepare. Students who have no understanding of why the experiment is important will not derive much knowledge from conducting it, nor will they remember or be able to use much of what they do learn.
Supervising the Experiment
At the beginning of the lab, review the purposes and procedures of the experiment. You might deliver a brief introduction explaining how the experiment relates to current developments in the discipline, or you might discuss the students statements of objectives. Ask for questions, clarify any ambiguities in the lab manual, and demonstrate special procedures now rather than interrupting the experiment later.
If both you and your students are well prepared, you will be free to perform your most important role, that of guiding the students development. Try to talk with each student at least once during the experiment. Technical and procedural matters can be handled quickly in a few words of advice or a very brief demonstration. However, your primary role is to help students master the steps of scientific inquiryrecognizing and stating a problem so that it can be explored, collecting data, forming and testing an hypothesis, and drawing a conclusion.
Helping students master each step is not an easy task. The 11 steps of guided design provide a good approach to problem solving:
- identify the problem,
- state the problem objective,
- list constraints, assumptions, and facts,
- generate possible solutions,
- determine the most likely solution,
- analyze the solution,
- synthesize the solution,
- evaluate the solution,
- prepare a report,
- implement the plan,
- check results.
The sequence is designed to provide a clear process for thinking through the complexities of real problems (Wales and Stager, 1977).
Refrain from Giving Outright Answers or Advice
If lab partners ask, Why cant we get this to come out right? try asking them a series of questions which leads them to discover the reasons for themselves rather than simply explaining why the experiment failed. Of course sometimes the reason will be relatively simple (You used hydrochloric instead of nitric acid.), but just as often the reason will be more substantiala matter of timing, sequence, proportion, or interpretation. Perhaps the student had the necessary data but has overlooked an important step in analyzing the results or is unable to synthesize a solution.
Its very tempting to help students by saying, Aha! I see where you went wrong, but unless you resist the temptation, they are likely to falter at the same stage in the next experiment. Students may become frustrated if they cant get a straight answer out of you, but they will also learn more.