PBS高端访谈:通过点燃圣诞树来表达对科学的热爱

 　　GWEN IFILL: Every year, fire departments in the United States respond to more than 200 Christmas tree fires, which are often more deadly than other house fires.

　　Tonight, we take a look at a program at the University of Maryland that uses Christmas tree burns to teach high school students, not only about fire safety, but about the relevance 1 of science and math.
　　The "NewsHour"'s April Brown has this report, part of our American Graduate series, a public media initiative funded by the Corporation for Public Broadcasting.
　　APRIL BROWN: This time of year, most people would buy a Christmas tree to make the holidays more festive 2. But scientist Isaac Leventon has a completely different plan for this one, which hasn’t had any water for a week. It’s all in the name of science.
　　ISAAC LEVENTON, Doctoral Candidate, University of Maryland: What’s really making us safe right now is, there is nothing within that tree for a good 10, 15 feet that can actually catch on fire.
　　APRIL BROWN: Leventon is a graduate student at the University of Maryland in the Department of Fire Protection Engineering. His large-scale, controlled burn of this tree and two others is the finale for a fire science class he created for high school students.
　　ISAAC LEVENTON: I think everyone at some point likes playing with fire, and that kind of keeps you here.
　　APRIL BROWN: The 10th and 11th graders will gather data from each burn, and eventually compare the heat release rates to determine which fire is more powerful. The class is free for the dozen students who live near the College Park campus and are accepted into the eight-week program.
　　ISAAC LEVENTON: That’s a really large fire. Whenever you see that amount of energy, now you know what that feels like.
　　APRIL BROWN: Leventon started it two years ago, with the goal of using fire to spark and grow interest in science, technology, engineering, and math, collectively known as the STEM fields, which experts say are critical to America’s future economic competitiveness.
　　But some educators have struggled to make these subjects engaging and relevant. In this class, setting fires does both.
　　ISAAC LEVENTON: For a number of them, you now have to study calculus 3 and chemistry and physics. In the one semester we have, I can’t teach them all of these things, but I can show them, here is how we can use basic chemistry to predict the temperature of any flame of our material, and then you can say, OK, maybe chemistry has an application.
　　APRIL BROWN: Students like Erin Stewartson and Pablo Ruiz do not receive high school or college credit for taking the class, which makes it all the more impressive they show up every other week for several hours after school.
　　ERIN STEWARTSON: My school doesn’t have an engineering program. And to do this for free, like, even if you don’t get credit, it’s still very good knowledge you can use.
　　PABLO RUIZ: It’s definitely given me a more solid idea of what engineering will be like.
　　APRIL BROWN: Some lessons are basic, like how a candle stays lit.
　　PABLO RUIZ: You have your ignition, and then kind of melts. And then the wick absorbs the wax. And then that melted wax, it evaporates, and then that’s what’s burning is that evaporated wick. It’s called fuel vapor 4. And that constantly burns until you put it out.
　　APRIL BROWN: Other are more complex, including one on fire tornadoes 6. Erin Stewartson wanted to learn more about them, so she and Leventon created one in the lab.
　　ERIN STEWARTSON: So, a fire tornado 5 is basically a normal fire plume 7, which is just something lit on fire, and then, when its — when an enclosure goes over it, which is like a rectangular enclosure, it creates like an angular momentum 8, which makes the fire spin into like a tornado, like a whirl.
　　And they actually do exactly what tornadoes do. Like, they pick people up and they take trees out of places, which is pretty crazy, how it forms. And just, like, seeing it happen in the lab, that was pretty amazing too.
　　APRIL BROWN: The class is structured just like a university level science course, with similar expectations and course work, like labs and tests. Here, though, the final project is presented to classmates and parents.
　　STUDENT: In America, there were 365,000 catastrophic house fires reported.
　　ISAAC LEVENTON: So it’s not just study something, measure something and present it, but really learn about what’s happening in the field and what are people doing and why does that matter.
　　APRIL BROWN: The introduction to what college classes will be like and discussion of potential career are two reasons Pablo’s mother, Norma Ruiz, is glad her son signed up.
　　NORMA RUIZ, Pablo Ruiz’s Mother: I think there should be more of these opportunities for high school students, especially the ones interested in engineering and the sciences, so that they can get a better idea of what they want before they actually get to college, because there’s nothing better than getting to college knowing what you want.
　　APRIL BROWN: Back in the lab, students continue to gather data, this time from a tree that’s been soaking in water for two weeks. It takes nearly five minutes for it to catch fire, compared to the drier tree which was almost fully 9 consumed in less than a minute.
　　ISAAC LEVENTON: It’s valuable to see how the fire is going to behave and know what that’s going to feel like. So we get that out of our tests. I wrote a number for what size fire it is. And knowing, OK, an 800-kilowatt fire, that means tree is burning 14 feet up into the ceiling, and I can feel it from 30 feet away, that’s — that’s just invaluable 10 experience.
　　APRIL BROWN: And even though Leventon is expected to get his Ph.D. very soon, the department hopes to find someone who can continue the class. A grant to fund it next year has already been approved by the Society of Fire Protection Engineers.
　　I’m April Brown in College Park, Maryland, for the “PBS NewsHour.”