We're in the midst of our unit on light. We talk about why we can't see a laser beam between the laser and the dot of light it puts on a distant wall. Then I modify the air in the room so we can see the beam. In the old days, physics teachers used chalk dust as a scattering agent. But chalkboards have been relegated to museums. There was a time when certain physics teachers used cigarette smoke. But smoking was long-ago banned from school sites.
What's a physics teacher to do? Several years ago, I came across "professional haze"/"fog in a can" in the Arbor Science catalog. It was a wee bit pricey, and you needed to use quite a bit of it to get the desired effect, but it worked. So for the past several years, that's how we turned my classroom into a laser light show. Eight bright, green laser beams sweeping through a darkened room with "visible air" is a memorable scene.Unbeknownst to me, a recent fire safety review of the school resulted in some changes on campus. The sensitivity of the smoke detectors was apparently increased. Significantly.
So as soon as I started fogging the room with my professional haze, blammo: klaxons and flashing xenon strobes! School wide. The students broke out in laughter and I had to follow along before sending them to join the rest of the student body out for the fire drill.
I thought I might make it through my entire career without causing a fire drill. I was wrong. Back in 1986--before my 22nd birthday--I actually had an unplanned fire in my classroom, but no detector detected and no alarm sounded. I was about three weeks into the profession (new school, new town, new state, first job) when a lighting ballast burst into flames. I knew where my nearest fire alarm was and I quickly pulled it. Nothing. The fire burned itself out, but it was startling to my very young self.
So many years later, when I set the alarm off unintentionally, all I could do was laugh.
