Learning About Senses with Onion, Gelatin

Learning About Senses with Onion, Gelatin

AP Psychology is a new course at Centreville High this year, and teacher Terri Ritchey's class is proving a big hit with her students because she often uses them in live demonstrations to illustrate her points.

"It's a different approach, compared to most of my other classes," said senior Rebekah Esmaili, 17. "This is psychology — it's about people. So because we have a classroom of people it's perfect to teach this way, rather than by doing experiments in a lab or [by using] animals. The way she runs the class is really original."

One day, for example, Ritchey wanted to teach her students how sight and taste interact, plus how smell affects taste. She also taught them about their sense of touch.

In one experiment, a girl was sent outside the room, and Ritchey told the class she'd be brought back in blindfolded and fed grape and cherry Jello. Then she'd have to see if she could tell which flavor was which, without seeing them.

While she was outside, Ritchey had two other students be her "control group," tasting the purple and red Jello samples to verify their flavors. When the girl came back inside and tasted the Jello blindfolded, she guessed that the purple sample was lime and the red sample was strawberry.

To the surprise of the entire class, Ritchey then told the class that, in reality, the subjects in that experiment were the two "control group" students who said the Jello samples were grape and cherry. That's because both Jello samples were really lemon flavor, and Ritchey had used food color to dye one purple and one red.

"It shows how the sight of something affects its flavor," she explained. "And it shows why chefs need to make food visually pleasing."

Next came a hilarious experiment involving three other volunteers, junior Sean Greer, 16, and seniors Blake Rushing, 17, and Brian North, 18. Blindfolded so they couldn't see the food samples they were about to be given, the three boys held their noses for two minutes to block off their nasal passages, breathing only through their mouths.

Then each boy ate pieces of onions and had to guess what food it was. They made faces and grimaced, while the students hooted with glee. Finally, Greer realized it was onion and told the others — and then all three boys filled their mouths with as many Tic Tac breath mints as they could hold.

"It was disgusting," said Greer after class. "At first, I thought it was lettuce I was chewing, and then, a red pepper. Then, when I let go of my nose, I found out it was an onion."

Rushing said he learned how "our sense of smell is connected to our taste. The texture made me think it was an apple."

North, at first, thought it was lettuce: "Then when I unplugged my nose, it reeked and I could taste it." Normally, he said, he avoids onions, at all costs: "I'm just not an onion fan."

Rushing agreed, saying, "There's nothing positive about onions — the texture or the smell." And although Greer said it was fun to participate in the experiment because it'll help him remember the lesson better that way, he said he also learned something else: "I'm not gonna volunteer again."

Before the sense-of-touch experiment, Ritchey told her students that their skin has receptors for pressure, pain, warmth and cold. Then a female student poked at the arm of blindfolded senior Laura Ramsey, 17, with a seam-measurer with two plastic points.

Ramsey had to tell when one pricking sensation became two, distinct sensations. She was able to do so sooner when the instrument touched her palm than when it touched her elbow. Ritchey explained that it's because people have more sense receptors in their arms than in their elbows.

"I was nervous that it was gonna be sharp and hurt," said Ramsey afterward. "I learned how sensitive our hands actually are." She also said that experiments using the students are a good way of teaching because "it's hard for me to remember things out of a book. I'll remember something more if I do [it] hands-on."

Esmaili was especially impressed with the Jello experiment and said that one will stay with her. "It showed that you rely more on your sight than on your taste or other sensations," she said. "I didn't realize the control group [students] verifying the Jello flavors were actually the subjects. They heard Mrs. Ritchey say what flavors the Jellos were and they saw the colors, so they didn't rely on their own senses of taste."

Overall, said Esmaili, the new AP Psychology course is great: "Today's class had so many demonstrations that it kept me entertained every second." And as Ritchey knows, clever teachers who can capture their students' attention are the ones able to make their lessons stick.