Center for Teaching and Learning

Teaching in labs

Labs provide students first-hand experience with course concepts and the opportunity to explore methods used by scientists in their discipline.In the lab, Department of Bioengineering
As a TA in a lab, you will need to know and review your supervising faculty member’s expectations for the experiment, plan clear explanations, and ask questions to stimulate student thinking. In addition, it is your responsibility to ensure that safety standards are followed.

Below you will find further information to help you in teaching your lab section and student comments about what makes a lab TA effective.


Preparing to conduct a lab

Your department might require you to attend weekly lab trainings or provide other ways for you to prepare for a specific lab. Make sure that you have enough information so that you would be able to conduct the experiment on your own.

What to know to prepare for your lab:

  • The materials and equipment you will need. Find out from your lab coordinator, lab tech, or supervising faculty member if there is anything you need to acquire on your own.
  • How much time the experiment will take.
  • How you will demonstrate new or difficult practices for students.
  • Potential obstacles or student questions. For example, which passages in the lab manual might be confusing? How you will explain them?
  • Safety hazards and procedures. As a TA, you are responsible for knowing the safety procedures relevant to the lab before you begin. Your department expects you to ask if any safety issues have not been explained well enough for you.
  • Clean up procedures. Courtesy is important in the lab, as is following all municipal, state, and federal guidelines for managing waste streams.
    • Find out how you will need to clean your workspace after the lab, and how much time you will need to allow for this. Plan enough time so that the workspace will be clean and ready for the next users before you leave the lab session.
    • Talk with your teaching team about the best ways to encourage and enforce student clean-up duties throughout the lab sessions. You do not want to do all of that clean up yourself!

Supervising lab activity

At the beginning of the lab: Tell students the purposes and procedures of the activity

Even if labs are designed primarily for independent student work, most students will appreciate a brief overview at the beginning of the period.

For example, you might:

  • Deliver a brief (2-5 minute) lecture on how the experiment relates to recent class lectures and/or to current issues in the discipline
  • Briefly discuss any other assignment you have given the students in order to prepare them for working through this experiment
  • Clarify any ambiguities in the lab manual
  • Demonstrate special procedures at the beginning of class rather than interrupt the experiment later
  • Ask for questions

If both you and your students are well-prepared, you will be free to guide the students as they do the experiment.

During the lab: Guide students’ learning

For example, you could:

  • 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.
  • Asking questions can help students master the steps of scientific inquiry. The best questions require time and thought to answer, so the best TAs push beyond simple ‘yes/no’ questions or confirmation questions like ‘You’ve got this, right?’ that lead students to answer quickly and affirmatively before they dig into it. Instead, here are some types of really useful questions:
    • Ask students to recognize and state a problem in order to explore it
    • Give opportunities for students to be collecting data
    • Put students in a position to form and/or test a hypothesis
    • Create a moment in which students can draw a supported conclusion
  • Facilitate the development of your students’ observational skills. As Chemistry Senior Lecturer Colleen Craig notes
, major stumbling block for undergraduate students in science labs is understanding what “counts” as a scientific observation. As a graduate student, you are likely to have an intuitive feel for which observations should be recorded during an experiment, and which are extraneous to the scientific question at hand. This may feel natural to you because of your years of prior training in science, and your students are just embarking on that sort of training.
Chemistry Senior Lecturer Colleen Craig advises:
  • If you notice something that you feel should be obvious to a student, try reflecting on why you noticed it, and walk the student through your thinking by asking leading questions.
  • Modeling expert-type thinking in this fashion is a powerful teaching tool, and helps empower students to analyze new situations on their own.
  • Furthermore, thinking about your own thinking (a process called “metacognition”) will help become a better expert in your field.
  • Refrain from giving outright answers or advice on conceptual parts of the work. If lab partners ask, “Why can’t we get this to come out right?” try asking a series of questions, which lead them to discover answers on their own, rather than simply explaining why the experiment failed.
    • Although it is tempting to help students by saying, “I see where you went wrong,” your students will learn more if you challenge them to figure out the answers on their own.
  • Be honest, professional, and considerate. Students expect TAs to be the authority figure in the room, but this does not mean TAs have to know everything!
Biology Instructional Manager Ben Wiggins notes:
  • Being honest about the parts of lab that you don’t know may seem scary, but it helps students frame the work as complicated and worthwhile. Your job isn’t to have all the answers, but to help them find the answers relevant to the course goals before they leave the room. Students know when a TA is faking it, but they also know and respect when they and their TA are in it together.
  • Be professional and considerate, which includes being friendly in many cases. Be on time to show your respect for students time and effort.

Assessing students’ performance in labs

Many supervising faculty will give their TAs a rubric to assess students’ performance in labs. Measurement of student achievement in labs is often based primarily on completion of the lab and a written lab report. Communication with the instructor is important to ensure that you are grading according to their expectations.

You may be asked to assess other aspects of lab performance, including:

  • Students’ observance of safety standards
  • Students’ preparation for lab
  • Students’ ability to perform lab techniques
  • Students’ understanding of the lab procedures

Whatever the professor and TAs decide to assess, it is crucial to communicate these criteria in writing to the students before the lab begins. It is also important to keep accurate records, particularly when assessing non-written aspects of student performance. Note that TAs, like all UW instructors, are required by the Family Educational Rights and Privacy Act (FERPA) to keep students’ grade information confidential within their teaching team.


Safety procedures

  • Safety is the most important issue when you are directly responsible for the health and well being of 25-30 laboratory students. Although dramatic incidents are rare, small accidents can be commonplace in a laboratory setting.
  • UW’s Laboratory Safety Manual – All staff in UW laboratories are required to have access to this manual.  Bookmark it!
  • If your department’s orientation does not cover safety procedures, the professor or lab coordinator in charge of the course will probably take responsibility for describing departmental policies. Anyone teaching or working in a lab is also expected to attend the laboratory safety seminar offered by Environmental Health and Safety (543-7262 or http://www.ehs.washington.edu). Sessions are offered just prior to the beginning of Autumn Quarter and throughout the year.
  • During the first few weeks of the quarter, you should demonstrate the proper techniques for lab procedures, e.g. decanting and mixing liquids, handling glassware, organizing a work area, using burners and other equipment such as gloves, goggles, face shields, etc. (i.e. all of the precautionary measures you now perform almost unconsciously, but which have not yet become familiar to your students).

All accidents–even small ones and near misses–should be reported to the UW Online Accident Reporting System (OARS). TAs are responsible for reporting accidents to their instructor (or whomever your department identifies), or directly to OARS. Find out from your supervising faculty member what process you should use to report accidents.