We had an incident in a high school physical science class where the substitute teacher left the room and several students engaged in dangerous behaviors with gas jets and flames. Fortunately, no one was injured and no damage occurred. I’m gathering suggestions on how to deal with this and prevent this in the future.
–Paula from Florida
First of all, you, the administrators, the substitute teacher, and the other students in the class at the time can be grateful that no injuries or damages occurred.
Experienced substitute or guest teachers in the sciences are hard to find, and good ones are an asset to the school and deserve our respect and appreciation. They make it possible for teachers to attend professional development programs or stay home when they are sick. Unfortunately, some students try to take advantage of substitutes, and once in a while, we hear of situations such as this one.
Several issues should be addressed:

• The students need to be held accountable for their behavior. It sounds like they waited until the teacher left the room (more on that later), moved out of their seats to a lab table, produced a flame with matches or a lighter, and turned on the gas. This would be a deliberate and serious violation of the class safety contract, far beyond a student accidently breaking a beaker or having to be reminded to wear goggles. The school administration should be the ones to impose consequences for this dangerous behavior, which may also have violated school policies.
• I’d be concerned why the guest teacher left the students unsupervised. I’m not sure what a good reason would be, but I’d ask for an explanation. Perhaps he or she was unaware of the potential dangers in a science lab? In any case, I would not want this person in my classroom again.
• This incident points out the need for having and using shut-off valves for utilities, especially gas, in lab classrooms. The gas should be turned off at all times when not being used for a planned, supervised lab investigation.

The incident is an opportunity to revisit your class safety contract. Does it specify that these rules apply when a another teacher, or no teacher, is in the room? Have a discussion with your students about appropriate behavior when another teacher is in the classroom. Establishing routines can be helpful so students know your expectations and can stay on task.
Ask your administrators to meet with the science department to become more familiar with the intensive level of supervision needed in a science lab to insure that students do not engage in unsafe behavior or vandalize the facility. The liability issue alone should get their attention. Occasionally in my school if substitute teachers were not available, the principal asked other teachers to cover classes during their planning time. If these teachers had to travel from another part of the building, it meant that students were unsupervised for a few minutes at the beginning of the class period, enough time for trouble. Frankly, if no substitute teacher is available, it might be better for the science classes to meet elsewhere.

Ask another teacher to keep an eye on your classroom and be a resource for your guest teacher (and make sure the gas is turned off and the storage areas are secure). If the substitute did not follow your plans or allowed students to behave in unacceptable or unsafe ways, you have the responsibility to share this information with your principal.
Safety should be a primary concern and you should not depend on a guest teacher to know all of the hazards of your labs. Even if you’re positive the teacher is credentialed in science and is familiar with laboratory routines and safety rules, don’t ask him or her to do a lab investigation with the potential for student injury, such as those requiring chemicals, live specimens, flames, projectiles, or heat sources.
See these archived Ms Mentor columns for related issues, including Plans for Substitutes  and Getting Started as a Sub.