Grading Guide

ENVR 411 lab reports and results are graded on presentation and interpretation of results in the same way you would be assessed if you were performing experimental research. Where appropriate this includes how close the value you report for your unknowns lies to the true value; that is, you are graded on the accuracy of your results. The experiments are relatively straightforward and "work", except for those occasional times when an instrument malfunctions or the extremely rare instance of a "bad" unknown. So grading on the basis of accuracy is as reasonable and rational a measure of lab technique and performance as anything else, and much less subjective than most.

The Lab Report

All students are required to have a laboratory notebook with numbered pages. Students may purchase these independently. The book should have a hard cover with secure binding at the edge and contain a minimum of 150 sheets sized 11.75 by 9.25 inches.

All information, data, calculations, notes, etc. should be recorded directly into this notebook and not on scrap paper. Writing should be clear and concise and in ink. Errors should be crossed out with a single line and marked with your initials, and the correction written next to it.

Before entering the laboratory, the student should become thoroughly familiar with the experiment and prepare the notebook to make record keeping and report writing more convenient.  The instructor will make office hours available ahead of the lab class so that you can consult with him if you have any queries or concerns (see under General Information.)

Basic Grading Procedure

Formal lab reports are required for all experiments. The required sections for your report are described in the link Writing Reports along with the number of points (out of 100) that can be awarded for that section. The semester grade is the average of the grades received for each of the reports.

The specifics for the presentation of your experimental data, analysis, and intrepretation will be shown in the individual lab instructions so please read these carefully before, during, and after your laboratory assignment.

Generally, points will be deducted for omissions, calculation errors, poor technique in the laboratory, failure to follow instructions, disorganized reports, poor lab book records, and accuracy of your results. Labbooks will be periodically reviewed during the lab sessions by the TA and instructor. Each experiment has its own tolerance or window within which your result must fall for a particular grade. For example, if the true value for your unknown is 1000 (in whatever units), and the tolerance for that experiment is 3 parts-per-thousand (ppt) or 0.3% relative error, your reported result must fall between 1000 3, (from 997 to 1003) to earn a grade of 30. If your result lies outside this range, but within the next set of 3 ppt windows, 1000 6, you earn a grade of 25, and so forth.

Report Due Dates

Lab reports are due one week after each experiment is completed unless otherwise stated by the instructor.  This means that they should be handed into the instructor at the beginning of the lab held the week following. Reports prepared hurriedly are extremely prone to simple calculation errors, which negate even the most painstaking lab work. 5 points will be deducted from the total score if the report is handed in during the 24 hours following this deadline. An additional 5 points will be deducted in each subsequent 24 hour period. Unless there are exceptional circumstances, which must be discussed with and approved by the instructor in advance, reports not handed in by 5pm on the Friday following the initial deadline will generate a score of "0" for that report. 

Extra Work

You may come in and work at extra times other than your normal day in the lab if you are unable to complete a particular experiment during the prescribed time. Please coordinate with the Teaching Assistant.

Working outside the normal laboratory hours (8.30am to 5.30pm) is not permitted.

Important Lab Practices

The Laboratory Instructors and Managers have very strong feelings about safety glasses, the instruments, and cleanliness:

Lab Safety Class. UNC Environment Health and Safety require all students who work in laboratories to attend a training session before they begin their work. More details about this class can be found at http://ehs.unc.edu/training/schedule.shtml

Safety Glasses. When handling any chemical, safety glasses (provided by the laboratory) must be worn. The first time a student is discovered working in the laboratory without safety glasses on, a warning will be issued; the second time, that person's name will be posted on a Safety Glass List in the laboratory; the third time, the person will be excused from the laboratory for that day. You do not wish to ask what will happen on the fourth such incident.

Laboratory Instruments. If the area around a laboratory instrument is left dirty, if the instrument is left on when it is requested to be turned off, or if an instrument is otherwise abused, all the people assigned to that instrument on that day will be penalized an appropriate amount of points on their report. Check your instruments before you leave!

Cleanliness. A student is responsible for keeping the entire area around his or her work station clean, including the shelves, during the entire time of the laboratory. Wipe up spills immediately. Everyone is to pitch in to keep common work areas, such as in the hoods, clean. It is not the job of the instructors to clean up after the students.