I suggest Chapter 6 of the following publication for a excellent discussion of laboratory class sizes, safety concern and cost of supplies.
America's Lab Report: Investigations in High School Science (2005)
From: DCHAS-L Discussion List [mailto:dchas-l**At_Symbol_Here**MED.CORNELL.EDU] On Behalf Of Mack Powers
Sent: Monday, April 14, 2014 1:02 PM
To: DCHAS-L**At_Symbol_Here**MED.CORNELL.EDU
Subject: [DCHAS-L] Class sizes
Last year or so there was discussion about class sizes for chemistry lab classes. Are those sizes mandated by a regulatory agency or suggested by a non regulating organization. The specific problem I need to address is potential overcrowding in high school labs designed for 24 students. Current attitudes in education are financily driven not safety driven.
Sent from my U.S. Cellular =AE Android-powered device
Mack Powers
High School Teacher