From:
Gmurczyk, Marta <00001fa03b1fa040-dmarc-request**At_Symbol_Here**LISTS.PRINCETON.EDU>
Subject:
Re: [DCHAS-L] [EXT] [DCHAS-L] Optimal Number of Students per TA/Instructor in General Chemistry Labs
Date:
Aug 25, 2025 20:14 UTC
Reply-To:
ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
Message-ID:
<CO1PR17MB53858D76D5575EAE33549B76EB3EA**At_Symbol_Here**CO1PR17MB5385.namprd17.prod.outlook.com>
In-Reply-To:
<SN6PR01MB49275434BEAAF769F4E9D8BFEE3EA**At_Symbol_Here**SN6PR01MB4927.prod.exchangelabs.com>
Dear Patricia:
ACS requirement for ACS-approved programs is:
- The number of students supervised by a faculty member or by a teaching assistant in an instructional lab should not exceed 25 to provide safe and effective instruction.
Please refer to the Safety Culture section ( ihttps://www.acs.org/education/policies/acs-approval-program/guidelines/safety-culture.html
in the ACS Guidelines for Bachelor’s Degree Programs (https://www.acs.org/education/policies/acs-approval-program/guidelines.html) for more context.
Marta
From: ACS Division of Chemical Health and Safety <DCHAS-L**At_Symbol_Here**Princeton.EDU>
On Behalf Of Leach, Patricia
Sent: Monday, August 25, 2025 3:01 PM
To: DCHAS-L**At_Symbol_Here**Princeton.EDU
Subject: [EXT] [DCHAS-L] Optimal Number of Students per TA/Instructor in General Chemistry Labs
[Actual Sender is owner-dchas-l**At_Symbol_Here**princeton.edu]
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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