From:
James Keating <james.k.keating**At_Symbol_Here**GMAIL.COM>
Subject:
Re: [DCHAS-L] Optimal Number of Students per TA/Instructor in General Chemistry Labs
Date:
Aug 26, 2025 17:27 UTC
Reply-To:
ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID:
<CAM1PioNTqy0z_K9y7PLuE2PLCSRNpCE2Op_7OppQbx=iyXFSsA**At_Symbol_Here**mail.gmail.com>
In-Reply-To:
<SN6PR01MB49275434BEAAF769F4E9D8BFEE3EA**At_Symbol_Here**SN6PR01MB4927.prod.exchangelabs.com>
Ms Leach,
Laboratory safety is of the utmost importance regardless of the number of students per lab supervisor.
Lab Safety must be an integral part of the curriculum. I am an Occupational Safety and Health professional and I always begin my safety orientation training emphasizing the fact that safety is part of the occupation or discipline you are performing and not merely ancillary to the task at hand.
This concept is an important part of every course syllabus and lecture I prepare. When I supervised work in a radionuclide laboratory I regularly reminded every employee of Lab Safety importance and performed continuing training.
I would suggest that laboratory principle supervisors remind students that after graduation they will probably work in a laboratory with hazards more serious that their school experience. Therefore, safety should remain an important part of their practices while in school and afterwards.
Jim Keating
Hello all,
We have had an explosion in the number of freshmen who are taking general chemistry this term, but funding has limited the number of TAs and instructors we have per lab room. The way the department has had
to deal with this is to increase the number of students from 30 to 38 per section (limited by the Fire Marshall’s maximum occupancy of the rooms). They work in groups of 3 (not ideal at all). We have adjoining labs, so our shortage of instructors has been
solved by having an instructor supervise two sections being held concurrently in a set of those labs. There is one TA per section.
In the past we have had 30 students (10 groups) supervised by a dedicated instructor (not working concurrent sections) and a TA, so about 15 students per person supervising. Now we can have as many as 38 students
(13 groups) being supervised by one person at times, as the instructor moves between sections. I feel this is not safe.
What do people think is a safe ratio of supervising people to students (or student groups)?
Thanks,
Patricia Leach
Lab Manager
Department of Chemistry & Biochemistry

SLC 3.513
Office: 972-883-6583
Cell: 469-891-6426
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