Labs prep young scientists at St. Christopher

By BETH DONZE
Clarion Herald

“Oohs” and “aahs” were in the air during science lab as seventh graders at St. Christopher School in Metairie discovered an anatomical quirk of frogs. Unlike human tongues, which are attached to the backs of our mouths, a frog’s tongue is connected at the front of its mouth.

“The back of the tongue is loose. I want you to flip the tongue out,” said their science teacher, Christen Picone, guiding the first of two dissection labs focusing on the parts of a frog’s head and trunk. “The frog uses the back of the tongue to grab a hold of its prey, and then it pulls it back in so it’s easier to swallow it!” 

The lab was planned and staffed by Picone with the assistance of a highly skilled volunteer: Dru Troescher, a retired St. Christopher science teacher who returns to campus  a few times a month to do fun labs with grades 1-7.

Troescher, whose 45 years of teaching in Catholic schools includes 21 years as a science teacher at the former Archbishop Blenk, said she often would encounter high school students with no knowledge of the metric system or of how to work in a science lab.

“Teaching is just a part of my life and I can’t stop,” Troescher said.“ I have this great need to come, especially to teach science. Kids get so excited about doing science, and doing labs at the elementary-school level is so important. That’s when you can really trigger their interest!”

At their first frog lab, gloved seventh graders, wielding tweezers, dissecting needles, probes and scissors, worked in pairs to examine the structures of a frog’s head. The teachers first drew their attention to the skin – the permeability of which helps the creature to breathe. The skin also protects the frog’s internal organs and camouflages it from predators.

A frog’s eyes are also multi-functional, sporting special eyelids (nictitating membranes) that help them see underwater. In another bizarre twist, the eyes help a frog to swallow.

“Every time a frog swallows, the eyes (retract) into his body to help push the animal down the throat,” Picone said, adding that frogs also are a great illustration of the saying, “You must have eyes on the back of your head.” They have 360-degree vision and night vision.

After cutting hinges loca ted at flanking sides of the mouth, the students were able to inspect their frogs’ two sets of teeth – the vomerine and the maxillary – located at the roof of the mouth.

“They’re so tiny you won’t be able to see them, but if you take your dissecting needle and rub it, you’re gonna hear it grate,” Troescher told them. “Do frogs chew their food? No,” She said. “So why have teeth? They use their teeth to hold onto their prey, and then they swallow it whole!”

Other features located by the young scientists included the internal nares (the opening of the nostril) the glottis, the gullet and the opening of the eustachian tube (which lead to the ears). While dissection of the frog’s trunk would have to wait until the second lab, students got a preview: Frogs do not have a neck or ribs, “which make the frog very vulnerable,” Picone said. “Our (human) ribs protect our lungs.” 

Throughout, Picone and Troescher used vocabulary that will serve their students well in high school and beyond, such as “anterior,” “posterior,” “lateral,” “dorsal” and “ventral.”

Troescher asked them to look at the spotted dorsal (back) and ventral (belly) portions of their frogs.

“Why do you think the dorsal side of the skin is dark and the ventral side is light?” Troescher asked the seventh graders. “For camouflage! When it’s crawling around on land it needs to be dark. When it’s swimming in the water and fish are looking up, it needs to blend in with the sky – so it needs to be light.”

Looking on was a regular visitor to St. Christopher’s science labs – their pastor, Father Raymond Igbogidi. The priest noted that his own schooling in his native Nigeria did not include much science.

“I was purely an art student, so this is an opportunity to catch up with science,” he said. “Being in the classroom reminds m e of those days when I was their age.”

After completing their two dissection labs, the seventh graders made origami frogs out of different types of paper and hypothesized how far they could jump, using their math skills to measure and average their test results.

“Some of my (past) high school students would show up without a knowledge of the metric system or how to do labs,” Troescher recalled. “We know what these students need to know when they go on to high school and college. We cover the standards, but we add some little twists and turns!”