To encourage students to engage in their own scientific investigations; to teach them that these investigations may take many forms; to demonstrate that the weight of new evidence can modify scientific theories.
This lesson makes use of a book called Exploratopia by Pat Murphy, Ellen Macaulay, and the staff of the San Francisco-based Exploratorium: The Museum of Science, Art, and Human Perception. (Little Brown & Co., 2007). This book was one of the winners of the 2008 AAAS/Subaru SB&F Prize for Excellence in Science Books (you can read about this prize at: Book Award). Exploratopia offers more than 400 kid-friendly and teacher-helpful experiments and explorations for curious minds. The book groups experiments in three types that are easily accessed and understood by kids as young as third grade:
- Exploring Yourself
- Exploring Interesting Places
- Exploring Interesting Stuff
The particular exercise your students will do is an experiment contained in Exploratopia's section on "Your Nose & Tongue." In it, students will work in small groups to perform a taste-sensitivity experiment described in the book that involves temporarily coloring their tongues blue with food coloring. They will then organize results in tally or graph form, discuss results, compare results with published accounts of this experiment, and finally, propose and design their own extension of the experiment and communicate results.
By performing this experiment, the class will learn about authentic science practices and obtain data on the distribution of taste sensitivity in class. They will begin to learn about "fair comparisons"—what in later grades are called by their proper scientific term of “controlled experiments.”
Students will gain valuable hands-on experience generating laboratory data. By comparing their results with published data, they also will learn about the collaborative nature of science in two ways. The first is in the class, where they will work in small groups and share results from the groups as a class. The second form of collaboration is found in the fact that in performing their experiment, they've joined a large international group: every scientist who ever asked a question about taste and investigated it in a systematic and scientific way!
Research shows that students at this developmental level may not understand the neutral stance of experimentation in science: The goal of an experiment is to produce data helpful for answering a research question. The goal is not to produce a specific desired outcome. It is therefore important in this lesson to emphasize the desirability of the spirit of "What happens if we do this?" Affirm the process, not the results. Highlight that all data have meaning, especially "surprising" data. While it might mean there was error and the experiment must be repeated, it also might mean new knowledge has been produced—and that's why it is surprising!
Before doing this lesson, each student should have proven impulse control to carefully paint a drop of blue food coloring in his or her mouth and swish it around to color the tongue blue—and then be able to focus on the next step! Students also need to be orderly, and control the experiment space of their desk top neatly.
BEWARE: The Blue Tongue Step is not the experiment. Some kids may get too distracted/excited/off task by the novelty of the Blue Tongue Step to complete the experiment. You can help them control themselves in advance by preparing for the fun visuals this produces. Then plan a “Tongue Show and Tell” and give each child 20 seconds to show off his or her tongue and look at it in a hand mirror before progressing to the next step of the experiment.
Make a model from a pipe cleaner by bending its length into parallel loops so that when it is placed flat on a surface it looks like a radiator.
Students will test each person in the class for taste sensitivity by determining how many of the taste sensory structures each student has on his or her tongue. These structures are called “fungiform papillae” (FP) and pronounced FUN-ji-form pa-PILL-ay, also known as “little pink bumps” on the tongue. Their Latin name translates to “fungus-shaped little pimples.” Kids may have seen these if ever they’ve eaten too much sour candy and looked in the mirror. The “little bumps” are over-stimulated and therefore enlarged fungiform papillae.
In this experiment, students will dye the tongue tissue blue to help them identify the FP—instead of over-stimulating them with sour candy. Once the tongue is swabbed blue, the reinforcement circle is placed on the tongue—NOT EATEN—to isolate a uniform sample of tongue tissue. Students then count the number of fungiform papillae and tally the results. As a teacher, you tabulate all class results and discuss the range of numbers of FP seen.
Pass out one pipe cleaner to each student. Ask each to bend it into a top-of-the-radiator shape—a series of equal-sized loopy bumps. Show them the one you made before class. Tell them: “Yours should look roughly like this.”
Explain to students that the pipe cleaner that you’ve bent in this shape is now a model—a scientific model. It is something we can touch and explore to help us understand a process in nature. This model can help us understand taste. Ask students:
- Where does taste begin?
- What specifically about the tongue enables it to taste? Its ability to curl? To make noises when you are teasing someone? (Demonstrate a raspberry sound, if this fits your teaching style!)
- How can we learn about taste from fungiform papillae?
- What kind of hypothesis could we make to predict something about fungiform papillae?
- How can our pipe cleaner model help us understand taste?
- (It begins on the tongue.)
- (Tiny structures called taste buds enable us to taste. Taste buds are located on tongue structures called fungiform papillae. Put your pipe cleaner model flat on the desk. Seen this way, it is a model of several fungiform papillae in a row, seen from the side. Now stand it up, so you just see rounded fuzzy tops. That’s called plan view: seen from above. That’s how we normally see fungiform papillae when we stick out our tongues, in plan view. They are part of all the pink tissue in your tongue. Try it!)
- (We will identify fungiform papillae and count them, and test them to see how sensitive we are to various tastes. Fungiform papillae contain taste buds—but the amount of taste buds they contain varies among each person. Each fungiform papillae could have one taste bud—or 15.)
- (The more you have, the more intensely you can taste things.)
- (In sideview, it shows us that there is a long side of each fungiform papillae. Up and down each of these sides is where the taste buds are located. Each taste bud has an opening called a “taste pore” through which chemicals enter. The taste pores are connected to sensory nerve fibers that take messages to the brain—which pronounces something sweet or salty or fatty—like the sensation of whipped cream in your mouth. That sensation was only named in 2000. It’s called umami (oo-MAH-me).)
Have students turn to page 40 in Exploratopia to see a picture—also in side view—of how taste buds are arranged on fungiform papillae.
Now explain to students that taste experiments have been performed for more than 100 years. As student investigators, they will join a long scientific tradition. They will see how their results compare with other scientists’ results. Other scientists' data suggest that 1 in 4—25%—of the population has a super amount of fungiform papillae. These people are called "super tasters." The particular taste sensation they are sensitive to is the “bitter” one. Ask students:
- What might our research question be for this experiment?
- How might we test that research question?
- (“Do we have 25% of super tasters in our class?” Or, “How many people in our class are super tasters?”)
- (Count the FP in each class member’s tongue and analyze our class data.)
Give students something bitter to taste, and write down how they describe the taste. Then compare all students’ answers. In the Development section, students will see if the classmates who taste the most have the most number of fungiform papillae.
Before students engage in the hands-on activity, explain to them:
“Scientists have done experiments whose results provide evidence that there are basically three taste types in people. There are: 1) People who like broccoli or brussel sprouts; 2) People who don’t like them; and 3) People who can’t even stand to put a tiny taste of them into their mouths.
People who are super tasters are especially sensitive to the bitter taste sensation associated with broccoli and brussel sprouts. We said earlier that most people have 1-15 taste buds on a fungiform papillae. If we knew how many fungiform papillae a person had, we could estimate the number of “workers” on the job–taste buds—they had.
That’s what we’ll do.”
Provide students with the Blue Tongue student sheet. Have them work in pairs to do the hands-on activity. You can conduct the activity with your students.
When everyone in the class has counted and tallied up the fungiform papillae, ask each student to report his/her results. On the board or overhead, tabulate the results in a histogram or stem and leaf plot. Ask students:
- What is the range of fungiform papillae in our class?
- What’s the middle number—the number most people have?
- What can we predict about our high-count fungiform papillae people?
- How can we test that prediction?
- (Whatever the low number and the high number are.)
- (In other studies, a person who has 10-30 fungiform papillae inside a standard reinforcement circle is considered average and called a Taster. Usually, about 50% of any group is a Taster. People with more than 30 fungiform papillae found inside the circle are called Super Tasters, and about 25% of any group is a Super Taster. The rest—25%—don’t have a problem with broccoli or brussel sprouts. They’re called Non Tasters. Use average/mean depending on how you’ve tabulated results.)
- (They don’t like broccoli.)
- (Ask them!)
Now have students conduct class interviews with each other about their results. Be sure to remind them to add “broccoli status” to the aggregate data sheet, and ask students to add it to their own lab notes. Ask students to draw conclusions in terms of:
- Do those with the highest number of fungiform papillae like broccoli?
- Do we have super tasters?
- Is our class typical, compared to other reports? Do we have 25% super tasters in our class? Do we have 50% tasters?
Summarize class findings for display by having each student create a “I Have Good Taste!” greeting card to be mailed to friends or family after the display period is over. To help them do this, students can use the I Have Good Taste student sheet. They should follow the directions on the student sheet.
To reinforce learning about the nature of scientific investigation, review the data for the class as a group, and discuss steps taken to generate data. Have kids give examples of data obtained, and how the class interpreted it, using other scientists’ results.
Then invite students to get into groups, and have them “apply for funding” using the Grant Application student sheet in which they propose conducting this study in another class to get more data from a larger sample size. Getting more data is a desirable trait in scientific studies because sample size, called "n" when it is large, helps assure results are true for the general population.
Successful grants must:
- Clearly explain the research question. (How many fungiform papillae do kids have?)
- Identify the theory the question addresses. (Taste structures are found throughout the tongue, not just in specific locations as once taught by the outmoded theory of the Tongue’s Taste Map. Taste abilities differ, and 25% of the population is super tasters.)
- Identify forms of evidence and how to generate them. (Accurate counts by standardized methods of student fungiform papillae through peer-learning sessions.)
As a class, listen to the last part of the interview with Exploratopia author Pat Murphy. In this part of the interview, she discusses the chapter in the book on language and linguistics. She asks the interviewer some questions about what words she uses for various things. After listening to this part of the interview, carry out a class activity where you ask students what words they use for some common things in their lives. This activity will get them thinking about how the sameword can be used differently by different people.
Have kids assemble “shoebox science” kits of the materials used in this lesson so they can check out the kits and test friends and family at home.
Suggest making a school-wide, hallway histogram that slowly builds, class by class, as more “grants” are successfully negotiated and the experiment originally performed by your class is conducted by peer instructors.
The following Science NetLinks lessons can be used to extend the ideas in this lesson:
The Exploratopia book is packed with experiments that explore the senses, familiar spaces, and activities. They include:
- Exploring Yourself: Take a Brain Apart (p. 68)
- Exploring Interesting Stuff: Getting to Know a Dollar Bill (p. 239)
- Exploring Interesting Places: The Bathroom and the Scoop on Poop (p. 115)