Laboratory

Introduction

Laboratory technique

Laboratory instruction can be a wonderful experience for the learner, who benefits from direct application and hands-on experience. D.S. Domin's (1999) work on a taxonomy of laboratory instructional styles defined several methodologies:

  • Expository instruction: students follow prescriped directions in a rote fashion
  • Discovery instruction: students are guided by the instructor toward a prescribed outcome, and try to form predictions and hyptheses as they go.
  • Inquiry instruction: students formulate their own problem statements, and there are not predetermined outcomes. Students take more ownership in designing the experiment. Instructors nudge students in the right directions with open (but leading) questions.
  • Problem-based learning: like inquiry instruction, students create their own problem statements and questions, but there is even less guidance by the instructor.

The higher the class level and the experience of the students, the more instructors can design the course toward greater freedom and individual discovery. Ideally, upper-level students should be shown how to explore the unknown as fellow researchers.

Methods

Two aspects of teaching lab that new instructors may find difficult involve pedagogy and logistics.  Pedagogy involves not only knowing how to teach, but the best methods of delivering the content as well.  Since some new instructors have little or no experience in this, their first semester might see some struggles and frustrations in this area not only from the instructor, but from the lab students as well.  Logistics present a similar problem, as it requires the instructor to design the lab experiments in a way that students will able to understand and complete them efficiently. This may be difficult as well if the instructor lacks of experience in this area.  But like with anything, practice and experience will lead to greater ability in pedagogy and logistics for lab instructors, which in turn could lead to more positive attitudes and performances of the lab students. 

The Pre-Lab
The Pre-lab is an important part of a lab course because it lays the foundation for whatever assignment or experiment the lab students will do.  Lab instructors must ensure that the students understand the purpose and concepts of any lab procedure they perform.  Instructors can do this by discussing the theories and principles behind the procedure, and instructing students on how to perform lab analyses prior to starting.  It is also necessary to go over any equipment and other safety procedures to prevent any careless accidents that can result from the lab student’s lack of knowledge in this area.

Pre-Lab Assignments
Pre-lab assignments can be a useful tool as well as they can better prepare students for the lab exercises by giving the students a familiarity with the lab process.  Pre-lab assignments can also help the instructors by making it easier to teach the theory the lab is based off of since students will have already had exposure to the principles that make up the theory.  The instructor should keep in mind what he/she wants their students to know prior to entering the lab when coming up with a pre-lab assignment.  Generally, concepts and theories or procedure and methods should be covered, but topics like troubleshooting, prediction of trends in data, and quantitative questions can be addressed as well.  The instructor should also make an effort to design the pre-lab assignment to correspond with what they plan to cover in the pre-lab introduction.  This helps ensure the students understand the material prior to entering the lab.  Formats for pre-lab assignments include worksheets, research assignments, quizzes, and preparing the lab notebook.   Each format has their own advantages and disadvantages, which are dependent on the outcome the instructor hopes to achieve from the assignment. 

Pre-Lab Introduction
Before actually starting the lab, the instructor must go through the pre-lab introduction.  First, the instructor will want to go over concepts from the lecture and address any concepts that will be covered in the ensuing lab.  It is important for students to understand how the concepts from lecture relate to the lab procedure, or else it loses all meaning. Next, the instructor should go over the lab procedures with the students.  This will help the students focus on the task at hand and can provide a final opportunity to clear up any discrepancies students may have with the lab and how it relates to the concepts covered in the lecture. Thirdly, the instructor should review examples of data analysis with the students in order to give them an idea of what to look for when analyzing their own data.  This can include giving hints about data interpretation or presenting them with mock data and allowing them to work with their lab partners to analyze.  Finally, the person leading the lab should go over equipment and safety considerations.  This should be done prior to every lab experiment, not just the first one.  Some general tips when doing the pre-lab introduction are to be consistent with the format in which you present it, and to be conscious of the amount of time you spend introducing the material before handing it over to the students.  You want to spend enough time so the students understand the concept and procedure, but not so much time that it causes frustration and anxiousness for the students waiting to start the lab.  The instructor should also ensure the pre-lab introductions does not interfere with the time needed for the actual lab procedure. 

During the Lab
While the lab is in progress, the instructor should make a conscious effort to move around the room from group to group.  This is done to ensure the students are on task and so that the instructor can assist a group should they appear to be struggling.  If the instructor notices multiple groups making similar mistakes, it may be necessary to stop the lab briefly to go over any questions.  The instructor should make an effort to ask pointed questions that encourage critical thinking, not just “Any questions?”  This can include asking questions that encourage reasoning when a group gets stuck, asking broad, open-ended questions when looking to initiate discussion, or asking focused questions when looking for a specific answer.  Asking how the lab relates back to the concepts learned in lecture can help with this as well.  As the lab draws to a close, the instructor should try to stop a few minutes early to summarize and address any questions.  After the lab is over, the instructor should send an email with a lab summary to all the students.
 

 

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