Curtain closing for District 203 students on Letterman?

Kids, silly science and a late-night comedian.

Put those ingredients together and - voila! - television gold.

"It's a good shtick for TV," said Lee Marek, a retired chemistry teacher from Naperville, who will be taking five students to New York City next week to appear on "The Late Show with David Letterman." It will be the 23rd time a group of students from Naperville Unit District 203 has appeared on the show.

"Dave interacts well with the kids," Marek said, "and I think it makes a good bit."

The occasional TV appearances, which have occurred during the past 17 years, might be coming to a conclusion with Letterman's approaching retirement.

But the adults who arrange the student cameos aren't mourning the end of the opportunity that has given 73 budding scientists a chance to be on a popular show. They're making like a good TV guest and going with the flow.

"We have no idea if we'll be returning," said Jaci Gentile, a science teacher at Naperville Central High School who has kept the New York-bound students organized and supervised on each "Late Show" trip. "We don't know, and it's not a concern, anyhow."

What is of concern to the five students who will audition before producers Tuesday is memorizing their lines. Each student must know the science behind all eight of the visually interesting experiments they might be asked to perform on camera during the official taping.

Samantha Xu, a sophomore at Naperville Central; Jakob Myers, a freshman at Naperville North High School; Jay Bhatia, an eighth-grader at Jefferson Junior High; Maddy Whirledge, a seventh-grader at Kennedy Junior High; and Emma Bednar, a sixth-grader at Kennedy, will get a shot at being on-air this year, but only three will be chosen to appear.

Using props, chemicals and equipment Marek had shipped specially to the Big Apple, students might drop a golf ball into a cup while both are in motion; propel a water bottle on a cart across the stage using burning ethanol; supercool liquid nitrogen to -196 degrees Celsius; or swirl a cup filled with water horizontally and in a circle without spilling.

Which experiments - and which students - will make the cut is up to the producers.

"Sometimes they pick a cheese ball in a straw; sometimes they pick a really complicated one," Marek said.

This year's most complicated demonstration is called "Jumping Ring," he said. It uses an electromagnet and an apparatus Marek got by trading with scientists from Texas A&M University to propel a metal ring into the air. The student then will cool the ring with liquid nitrogen to show changes in the force of repulsion.

Letterman might find it funny.

"We tell the kids he's going to say things that are a little bizarre," Marek said. "He might ask you if you're married or something like that. Your first job is to be a kid. What you don't want to be is a smart aleck and try to upstage him. If you do that, it'll be most unpleasant for you."

Students practicing their science and their lines are planning for a nerve-wracking but fun TV experience. Chosen by teachers to audition at the district level, these students, like eighth-grader Jay Bhatia, enjoy hands-on activities or have a knack for science.

"I'm excited about what I'm doing - it's the T-shirt shooter," Jay said about a PVC pipe contraption inside which he will create a combustion reaction to propel "Late Show" T-shirts into the audience. "The rest of them are pretty cool, but I'm pretty excited about the T-shirt one. In my opinion, that's the coolest."

The show featuring District 203 students' five minutes of fame is expected to air at 10:35 p.m. Tuesday on CBS 2, but the schedule could change.