Laboratory Instruction

The labs were terrible. I thought I was going to make things come together by doing something practical, but the TA never knew if the experiment was going to work or not, and usually he just sat in the corner waiting for lab to be over. My roommate was lucky. Her TA walked from group to group and helped them figure out what was happening. Like me, she's not a science major, but she plans to take more courses and I wouldn't be caught dead in another science course.  --Freshman student

Although labs are run differently by different departments and TA responsibilities vary, there are some general guidelines to follow.
 
 

LAB PREPARATION CHECKLIST Perform experiment Know the theory Prepare demonstrations Check for supplies/first aid Anticipate safety problems Locate safety equipment Clarify learning objectives Return lab reports promptly

BE PREPARED! Read the experiment before going to the lab, and make arrangements to actually conduct it. Students lose respect for the course, the TA, and themselves when their uncertainties aren't alleviated by a capable, confident TA.
  a. Perform the entire experiment in advance--there is no guarantee it's going to work as advertised in the lab manual. Remember how frustrating and disappointing a flopped experiment is?

b. Read and study the theory on which the experiment is based--otherwise, some student may ask you a question that you can't handle.
 

CHECK THE EQUIPMENT AND MATERIALS before class, if a demonstration will be conducted. (See section on demonstrations.)

KNOW WHERE THE SUPPLY STOREROOM IS and where the first aid kits are located.

OBSERVE ALL SAFETY PRECAUTIONS. Know where safety showers, fire extinguishers are located. (See section on Safety Considerations.)

CLARIFY OBJECTIVES. It is usually appropriate to go over homework questions or provide some background before students work on their own.

Many students are frustrated by unclear objectives during labs--your job is to clarify objectives and assist students in attaining these goals.

RETURN GRADED LAB REPORTS AS SOON AS POSSIBLE. Establish criteria for grading and explain them before students complete the lab exercise.

Often, your primary instructor will establish guidelines for grading so that a large class with many lab sections has consistency.
 

What can I do to manage students during a lab?

As you are well aware, a lab is different from a lecture class:  teaching a lab often involves several one-on-one situations, a highly interactive format.  Experienced TAs recommend that you learn the names of all your students:  it is easier to guide the class and facilitates learning when students realize you respect them.  Above all, don't sit in a corner and grade papers!!  A good TA moves around the classroom, identifying problems before they occur, and helps students step back and evaluate what they're doing.

What is the point of these lab sections?

Lab exercises and formal experiments are "hands-on" formats that provide  students a chance to link together the theory and other experiments of the course.  Experienced TAs remind you that some labs are not explained during the lecture or they may not be discussed coincidentally to the lab.  As a lab TA, you are expected to give a brief "lab talk" in which you:  (1) outline the lab objectives and (2) cite the ways these learning objectives mesh with the course theory.

Is it important for students to produce the expected results?

The goal of all scientific experimenters is to EXPLAIN WHATEVER RESULTS OCCUR.  It's difficult for students who are accustomed to receiving grades for being "right" to accept this, even when they're assured that perfect replication of results is just not possible.  As a TA, you can alleviate some of the major errors as you move from station to station during the lab.

What should I look for when I evaluate lab reports?

First, check with the supervising faculty for overall depth and critical content; in large lectures with many small lab sections, grading is often standardized.  Next, read through a random selection of the reports to get a feel for the level of comprehension: students are novices and often use inexact language and roundabout discussions to explain their results.  Finally, consider the value of a well-explained "wrong" result:  what are the scientific skills we hope to foster during labs?

How should I prepare for lab?

Experienced TAs suggest you read the experiment and do the exercise once before lab so you can anticipate areas in theory and procedure where students might have problems.  Being familiar with all equipment, chemicals, or specimens used during a lab will enable you to handle any situation that arises.

What else should I know before I run a lab?

• Know who your resources are when equipment malfunctions, reagents are used up, or a specimen crawls under the cabinets!
• Talk to TAs who have taught that lab.
• Realize that you are qualified to teach undergraduates effectively; none of your students has your background, preparation or scientific ability.
• One of the best ways to find out what you need to know before lab is to teach a lab, recognize what areas gave you problems, and prepare for the next lab.

 

What about safety issues?

TAs should know the safety regulations in their department as well as the University and State policies.  Students should be made aware of these regulations at the beginning of the semester and reminded of them as necessary.  Experienced TAs find that most safety issues involve students mishandling laboratory equipment, chemicals, and specimens.  Again, many problems can be alleviated by an alert TA making rounds during the lab (refer to the section on Safety Considerations.)

How can I get my students to prepare for lab?

There's always that old stand-by, the "pop quiz."  Alternate methods are:  to require students to outline the exercise or procedure in a notebook before coming to lab, to encourage group discussion of expectations before each lab (or of results at the conclusion of each lab), or to collect written predictions from each student about the day's lab before class begins.  At a more esoteric level, students will innately prepare for labs that they find challenging but do-able, informative but not confusing, and relevant to either the course goals or their future goals.  Some students prepare simply because the TA is enthusiastic and supportive--hence, a lot of learning gets done during labs!