Chapter 7. LAB 7 Skills in the Laboratory III: Competency Exam

Learning Goals:

• Check equipment use performance of others using a checklist of predefined criteria.
• Demonstrate an acceptable level of mastery for use of the spectrophotometer, compound microscope, balance, micropipettors, pH meter, and Vernier caliper.

7.1 Background

Tools are important in laboratory research and they must be used correctly to avoid misuse that results in incorrect application or measurements, or damage to the tool, the user, or the lab.

In Lab 2 you learned the SALI strategy that trained you to approach new instrumentation in a well-defined formal way to maximize accuracy and safety in the use of new instrumentation. This is a skill you develop with practice over time where your knowledge, coordination, and reflexes become integrated to make you a skilled tool user. Specialists including surgeons, electricians, and plumbers spend years learning to use the specialized tools that they need to master their professions. Even when learning how to drive, one must pass both a written exam to evaluate how well they know the “rules of the road,” and a road test to evaluate how competent they are in actually driving a vehicle.

The tools you were trained to use in Lab 2 are standard pieces of laboratory instrumentation in biology research. Even if you encounter a more modern version of one of these tools in someone’s lab, the measurements and principles underlying their use will probably be the same. Importantly, there will always be a standardized protocol (standard operating procedure or SOP) for the correct use of the tool for the sake of safety, cost, and accuracy.

The Competency Exam is designed to ensure that you have internalized and can apply the rules for the correct use of: 1) the compound microscope; 2) spectrophotometer; 3) Vernier caliper; 4) centrifuge; 5) micropipettor; 6) digital balance; and 7) pH meter. In preparation you should have completed a Strategic Approach to Laboratory Instrumentation (SALI) for each piece of equipment in the tools lab. You should keep your SALIs as reference materials for each lab in which you use these instruments. The week before the Competency Exam, you should practice these pieces of equipment in the Biology Learning Center. The table of “instrumentation competency topics” (Table 1) lists skills to develop as you practice using each piece of lab equipment.

7.2 Activity 1: Instrumentation Practice (prelab)

Purpose

Visit the Biology Learning Center the week before the Competency Exam to practice use of lab equipment. Practice is a key element in the learning of a new tool as stated by the SALI, but practice alone is not sufficient. You need an expert to critique your technique or “criteria” in a rubric to follow so that you know whether or not your technique meets expected standards. If you do not know how to blank the spectrophotometer correctly, what impact will that have on the accuracy of the absorbance reading for your solution?

Learning Objectives

After successful completion of this activity, you should be able to

• Standardize a spectrophotometer with the correct blank and read the absorbance of a solution at the proper wavelength
• Focus a prepared tissue slide under a compound microscope at 400X magnification with proper resolution and good illumination, and count the number of cells in the field of view
• Standardize a pH meter with 3 standard solutions and read the pH of an unknown solution
• Weigh solids and liquids on a balance
• Balance an even or odd number of tubes in a microcentrifuge
• Measure an object with Vernier calipers to 1/10th of a millimeter
• Demonstrate how to avoid damage to a micropipettor
• Use a micropipettor to accurately measure specific small volumes of liquid
• Calculate solution dilutions

Procedure

1. Review Table 1 Instrumentation Competency topics and the SALIs that your group members prepared for the Tools prelab. You will be tested on the spectrophotometer, microcentrifuge, compound microscope, pH meter, micropipette, balance, microcentrifuge, and Vernier caliper.
2. Create a chart in your lab notebook similar to Table 2 Instrumentation Review. Test your knowledge of the tool, by making a checklist from memory of the standard operating procedure (SOP) for the instrument and important safety issues. SOPs are common in labs or industry and denote the standard protocol used to operate any tool for a specific purpose.
3. You should already have an SOP as part of the “Safety” section of the SALI. Refine your SOP as a checklist of items you will know to perform to make sure each component of the instrument is set up to obtain the best information from the tool. Use the on-line videos of the tools to help you check the completeness of your SOP.
4. If you cannot produce an SOP from memory you should not touch any instruments until you can because you do not have the knowledge or skill required to safely use the instrument.
5. Once you have produced your SOP checklist, you may want to ask an instructor to scrutinize your list for its accuracy. This is your opportunity to resolve any questions you have about the tools.
6. Practice with each piece of equipment and make note of any important concepts. Try developing analogies that aide you in remembering how to standardize the piece of equipment, collect data or record measurements with it and the rationale for the process.
7. Ask another student to test you with a 5 minute timed run-through of the equipment as if you were actually taking a competency exam.
8. If you are confident that you know each instrument, its parts and their function, the order in which to approach the instrument based on an SOP, and your ability to produce reproducible results, and have the coordination and dexterity to use the instrument correctly, then you are ready for the lab activities.

7.3 Activity 2: Student Assessment of Instrumentation Use with a Rubric

Purpose

The purpose of this activity is to familiarize you with the “examiner rubric” that you will use to score your instructor’s use of a piece of equipment. You will also use this rubric for the competency examination. Your lab instructor will use the lab equipment in a manner that may include mistakes or omissions of correct tool use and you will score their technique. The technique the instructor uses may warrant a score from “0” to maximum value. You will check your score against the instructor’s answer key and note what you did or did not observe during the demonstration.

Avoid Academic Dishonesty during this activity: a) Keep your examiner rubric covered b) Do not talk or discuss scoring with classmates, and c) Do not look at another student’s examiner rubric. You will have an opportunity for class discussion after each evaluation.

Learning Objectives

After successful completion of this activity, you should be able to

• Properly use a list of criteria, the examiner rubric, for evaluating tool use
• Score your instructor in the use of equipment and aim for a performance score in 100% agreement with the instructor key

Materials

48 examiner rubrics, 2 per person

Procedure

1. Turn to the correct “examiner rubric” and place it next to a space in your lab notebook. Label the top of the sheet the piece of equipment that you are about to score.
2. Watch your instructor demonstrate the piece of lab equipment and score their skill with a check for every correct response and a minus sign for every incorrect response in your lab notebook next to the correct item. You will do this individually and should not share your scoring with your group members.
3. Tally your points and write the total in your lab notebook.
4. Check your lab notebook answers as the instructor displays the answer key and rate your ability to properly score the instructor’s technique.
5. As a class, discuss the following points:

6. Score your instructor again as he or she repeats the process with a different instrument, repeat the class discussion points following each piece of equipment.
7. Evaluate your ability to assess the instructor after the trials are complete. If you had a tendency to mark procedures incorrect that are correct then you may not be observing closely enough or you may not be sure what constitutes an acceptable performance. If you are marking procedures correct that are incorrect, then you may need to review the actual steps for use of that piece of equipment.

7.4 Activity 3: Peer-review of Instrumentation Use

Purpose

This activity serves as a formative assessment of your ability to determine the degree to which someone is properly using equipment and whether you are able to evaluate them fairly. After your group completes each station, you will take your competency exam, Activity 4.

Learning Objectives

After successful completion of this activity, you should be able to

• Score a trainee in the proper use of equipment using an examiner rubric.
• Evaluate a trainee’s ability to standardize a spectrophotometer with the correct blank and read the absorbance of a solution at the proper wavelength.
• Evaluate a trainee’s ability to focus a prepared tissue slide under a compound microscope at 400X magnification with proper resolution and count the number of cells in the field of view.
• Evaluate a trainee’s ability to standardize a pH meter with 3 standard solutions and read the pH of an unknown solution.
• Evaluate a trainee’s ability to weigh solids and liquids on a balance.
• Evaluate a trainee’s ability to balance tubes in a microcentrifuge.
• Evaluate a trainee’s ability to measure an object with Vernier calipers to 1/10th of a millimeter.

Procedure

1. Obtain three examiner rubrics per group member. See table above.
2. Select one group member to serve as the trainee for Station 1: Micropipettors and balance and the remaining group members will serve as examiners. If you are an examiner, place the station 1 examiner rubric next to a space on a clean sheet in your lab notebook.
3. Read the station instructions out loud to the trainee and set the timer for 5 minutes and start. While the trainee performs the task, score them in your lab notebook using the examiner rubric. Do not talk during the assessment or share your answers at this time with your group members.
4. Tally the score from all three examiners onto the score sheet for Station 1 and include examiners’ name’. One person will enter the data into the survey link for Station 1.
5. Compare scores with your other group members and discuss the differences in scoring for a few minutes by considering the following points.

6. Select another group member to serve as the trainee for Station 2: microscope. Turn to the microscope examiner rubric.
7. Tally the score from all three examiners onto the score sheet for Station 2 and include examiners’ name. One person will enter the data into the survey link for Station 2.
8. Compare scores with your other group members and discuss the differences in scoring for a few minutes by considering the same points as before.
9. Repeat this process for the remaining stations: Station 3: spectrophotometer and Station 4: pH meter. Use a different trainee for each station so that all group members have served at least once at one of the four stations.
10. When you are done with the peer-review and entered your scores into the survey, submit your data.
11. Turn in your initialed score sheets and lab notebook score sheets to the instructor to receive 5 points towards the competency exam.
12. As a group review the material during the five minute mark before the exam.

7.5 Activity 4: Competency Exam

In this activity you will be tested on your expertise with laboratory equipment use by evaluating a videotaped subject using the different pieces of equipment. This is an individual examination, although you are evaluating the subject in the video, your competency score will be computed using the accuracy of the points you give to the subject’s performance with the tool.

Avoid Academic Dishonesty: a) Keep your answers covered by turning over your sheet once you have scored a videotaped session or answered a question, b) Do not talk or discuss answers with classmates, and c) Do not look at another student’s answer sheet.

Learning Objectives

After successful completion of this activity, you should be able to

• Evaluate proper use of equipment using the examiner rubrics.
• Balance an odd number of tubes in a microcentrifuge
• Read a Vernier scale

Procedure

1. Obtain a competency exam answer sheet from your instructor.
2. Complete your answer sheet in pen. Place your name, SBU ID#, section number, date and time legibly at the top of the answer sheet.
3. Your instructor will walk you through the exam. There should not be student discussion and no questions will be answered at this time.
4. You will be asked to observe the subject using a tool and record what they did correctly or incorrectly using the rubric. Your grade will be based on your knowledge of the tool and the accuracy of your evaluation of the subject’s use of the tool.
5. Once the exam has ended give your answer sheet to your instructor. Your instructor will grade your exam and return it to you the following week.

7.6 Activity 5: Polymerase Chain Reaction I

Bring a GMO suspected food item and perform Activity 1 and 2 of the PCR I lab (Lab 13).