The ACS division of Chemical Education (http://www.divched.org) has published the following
        "Minimum Safety Guidelines for Chemical Demonstrations":

Demonstrations must pose no danger to the audience or presenter, and approved disposal methods must be specified.
            Chemical Demonstrators MUST:
                    1.  know the properties of the chemicals and the chemical reactions involved in all demonstrations
                            presented.
                    2.  comply with all local rules and regulations
                    3.  wear appropriate eye protection for all chemical demonstrations
                    4.  warn the members of the audience to cover their ears whenever a loud noise is anticipated
                    5.  plan the demonstration so that harmful quantities of noxious gases (e.g. NO₂, SO₂, H₂S) do
                            not enter the local air supply.
                    6.  provide safety shield protection whenever there is a the slightest possibility that a container,
                            its fragments, or its contents could be propelled with sufficient force to cause personal injury.
                    7.  arrange to have a fire extinguisher at hand whenever the slightest possibility for fire exists.
                    8.  not taste or encourage spectators to taste any non-food substance.
                    9.  not use demonstrations in which parts of the human body are placed in danger (such as placing
                            dry ice in the mouth or dipping hands into liquid nitrogen).
                    10.  not use "open" containers of volatile, toxic substances (e.g. benzene, CCl₄, CS₂, formaldehyde)
                            without adequate ventilation as provided by fume hoods.
                    11.  provide written procedure, hazard, and disposal information for each demonstration whenever
                            the audience is encouraged to repeat the demonstration.
                    12.  arrange for appropriate waste containers for and subsequent disposal of materials harmful
                            to the environment.
                        Revised 4/1/95.  Copyright 1988, ACS Division of Chemical Education, Inc.

The NSTA has similar guidelines, on the web at   http://www.nsta.org/pdfs/SafetyGuidelines.pdf