Blog

10:15: Lab Exams: The Real Deal

presented by Carter Stanfield from Pearson


Session is described as covering ways to administer hands-on exams in the lab, awarding defensible grades for lab projects, and documenting the results. Carter is co-author of HVACR Fundamentals (hvacrfundamentals.blogspot.com).

Why give shop exams? More like field work, grades demonstrated skills and not the knowledge that goes along with the skills, raises expectations, and students pay attention. What better way to test brazing than to have students do brazing. Raises student expectations because it breaks down the “group” with turning in papers for checking off purposes and forces each and every student to perform for a grade. This causes students to pay more attention in lab rather than just relying on their cohorts for answers. By using shop exams you can change the attitude of the students to be more “hands-on”. Students go from a compliance mode to a competence mode.

Compliance mode: you tell me what to do and I do it. Competence mode: I need to know how to do this. If I do not know how to do it perhaps I should learn. Competence requires practice.

Types of exams

One comprehensive project, series of shorter exams, or a troubleshooting round robin.

Comprehensive project:

  • Should cover most areas of a course
  • Closest o field competence test
  • Best suited for advanced courses
  • Good students really enjoy
  • Poor students struggle
  • Done over a longer period of time than a typical exam

An example: Install split system

  • Refrigerant lines
  • Power wiring
  • Control wiring
  • Evacuation/recharge
  • Final check and test
  • One week time allowed

Another example:

  • Recover refrigerant
  • Remove reversing valve and compressor
  • Install reversing valve and compressor
  • Evacuate and recharge
  • Final check and test
  • One week time allowed

The downside is that the units can get destroyed over time. Scheduling with larger classes is a challenge.

Series of short tasks:

  • Work well in introductory course
  • can be completed in less time
  • can be mixed with written exams

Examples:

Put labels on components, students write components (1,2,3, etc):

  • Name
  • Refrigerant state
  • Refrigerant pressure
  • Refrigerant temperature
  • Saturated, superheated, subcooled

Another example: Have gauges and thermometer on system and determine condition:

  • Saturated
  • Superheated
  • Subcooled

Another example: Have refrigerant recovery cylinders with gauges and an IR thermometer. Students identify refrigerant in cylinder from a list. Make sure refrigerants are far enough apart so that it is not overly confusing.

Refrigerant service tasks:

  • Flaring project
  • Swaging project
  • Light a torch
  • Small soldering project
  • Small brazing project

The short projects have the students use the information rather than just test on the material through multiple guess testing. If the student is paying attention as the exam goes on the good student will learn from the other students mistakes or instructors corrections.

Evacuation and recovery projects

  • Use core tool on valve cores
  • Connect recovery unit
  • Connect vacuum pump

Basic Electrical tasks:

  • Build basic circuits
  • Read resistance
  • Read voltage
  • Read current
  • Change cartridge fuse
  • Use non-contact voltage detector

Motor tasks:

  • Types of motores
  • Check windings
  • Wire and operate motors

Control System tasks:

  • Identify control components
  • Check control components
  • Wire a heat-cool thermostat
  • Check a heat-cool thermostat

Troubleshooting Round Robins:

  • Series of problems – one for each student
  • Challenge is to identify the problem – not fix it
  • No parts changing
  • Change systems after a period of time
  • No talking
  • Students are not given symptoms
  • Instructors do not answer questions
  • Instructors will not tell students if they are correct
  • Answers on paper only

Answers have five parts:

  • What is system doing wrong?
  • What is causing this?
  • How did you determine this?
  • How can this be corrected?
  • How much will this cost?

Assigning Lab Grades

Two basic types of systems are pass fail or letter grades.

Pass fail:

  • Simple
  • Tends to promote mediocrity
  • Most passing work is of minimal acceptable quality

Traditional grades:

  • Most familiar grading system
  • Grades below A motivate students
  • Can be difficult to determine grades
  • Grading tends to be subjective
  • Grading can vary between instructors

Rubrics to the Rescue:

A guide listing specif criteria for grading or scoring academic papers, projects, etc. Adds objectivity to something that is an inherently subjective process. It boxes the instructor into boundaries for the grades. Provide a framework for determining grades. Shows students how their grade is determined. Reduces grade discrepancy between instructors. Demonstrated defensible grades.

Rubrics can use points for positives but also as demerits. Rubrics are built on standards. Standards can be characteristics of the process used; characteristics of the finished product; time taken to finish; number of attempts required. Standards should be definable, not vague, observable, and measurable.

Step 1: List standards

  • Too few give incomplete assessment
  • Too many standards can be confusing
  • 4-5 is good

Step 2: Standard Weight:

  • Can be equal across all standards
    • example: 5 standards each counting 20%
  • More important standards can count more
    • Example: 4 standards at 15% and 1 at 40%

Step 3: setup the scale

  • Numeric 1-5 or 1-10
  • Alpha: A, B, C, D, E, F
  • Descriptive: Superior, excellent, good, fair
  • Numbers work the best

Step 4: Assessment

  • Upper and lower limit examples
  • Examples of each level on the scale
  • Time
  • Frequency
  • Repetitions

*** Need to make sure you have a plan for students with disabilities on how to fairly complete these assignments.

Administering Shop Tests

No surprises:

  • Inform students early in term about shop exam
  • Make sure they do all procedures in lab during term
  • Allow them to practice

Timing:

  • Spread shop exam over a week
  • Fixed time slots are easiest to manage
  • 2 hours per time slot
  • Allow time between time slots for packing up and resetting
  • Students choose a time slot on sign up sheet
  • Use hours of availability on written exams…..

Test conditions:

  • Lap proctor at all times
  • Limit number participating in exams at one time
  • OK to have students in different classes in shop at one time
  • No group work
  • No talking
  • All answers written only
  • Students are not told if their answer is right during the exam
  • All exams graded by the same instructor

Paper mountain:
15 lab sheets per course
x 10 different courses
x 20 students per course
= 3000 Lab sheets