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The incredible
growing gummi
bear
by Patty McGinnis
E
very student is familiar with gummi bears,
those rubbery candies in the shape of a
teddy bear. Gummi candy was first invented
by German candy maker Hans Riegel, who
founded Haribo confectionery in the 1920s (Bellis).
The original gummi candy, made up of corn starch,
corn syrup, sugar, color, and flavoring, owes its distinctive texture
to edible gelatin (there are
some brands of gummis available that do not contain gelatin). Gelatin, a pure protein obtained from the skin and bones
of animals, is a food additive used
as a gelling agent in a number of
foods, including marshmallows,
whipped toppings, and canned
ham (Gelatin Innovations 2009).
Use your students’ love of
gummi bears to encourage
full participation as recommended in the National
Science Education Standards (CSMEE 2000) and
to review and reinforce
process skills—skills that
are critical to helping children develop scientific ideas
(Ash 2001). Process skills are
transferable, integral to many
science disciplines, and include observing, predicting,
measuring, and interpreting
data (Padilla 1990).
I like to conduct this
activity at the onset of the
school year so that I can
quickly assess my students’
process skills and their ability to read, follow directions, and work cooperatively. Although students
have been taught how to measure in previous science classes, I often find that many do not know
how to correctly align a ruler with the end of the
object being measured, have little idea of the units
that exist between numbers on a ruler, or do not
know how to correctly use a triple beam balance.
Because this lab activity repeats the same measurements for two days in a row, it ser ves as a form of
formative assessment; I can determine if students
have corrected errors in their methodology from
the previous day’s activities.
Materials note: When you choose a brand of gummi
bears, be sure to do a trial run, because some brands
will dissolve rather than expand. Black Forest gummi
bears work well.
The activity
On the day of our lab, students walk into the room
and are greeted with “I’m a
Gummi Bear,” an animated
music video with a catchy tune
sung by a green dancing gummi
bear (see Resources). I hand
each student a gummi bear and
a clear, plastic, three-ounce cup
with directions not to eat the
bear. Students must wear chemical splash goggles during
the activity. The question
“What will happen to a
gummi bear when you
put it in water overnight?”
is posed to the class. As a
class we discuss what usually happens when objects are
put in water (e.g., they sink,
float, dissolve). Students are
then asked to record their
prediction and reasoning for
their prediction as to what
they think will happen to the
gummi bear.
Students fill in a data table
that includes descriptive
obser vations of the gummi
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bear such as texture, appearance, and smell. Next,
students place the bear on their desk or lab station
with the bear on its back and use a centimeter ruler
to measure the bear’s length (head to foot), width
(across the widest area of the bear), and height
(distance from the heel of the bear’s feet to the tip of
its toes while the bear is lying on its back on the lab
table). I demonstrate how to measure the bear using
a student volunteer and a meter stick. The student
lies down and pretends to be a gummi bear while
I show the class how to take the measurements.
These measurements are used to obtain estimated
volume in cubic centimeters. Note that due to the
irregular shape of the gummi bear, this method will
yield an estimation of volume. If you wish to be more
exact, ask students to calculate volume using water
displacement. Although somewhat messier (the
gummi gets a bit slimy), it is more exact. A good
point of discussion would be to compare the two
methods and ask students which they feel is more
accurate and why.
It is fairly easy to determine if students are measuring or calculating incorrectly, because the bears
have identical measurements (unless a bear has
been squashed due to packaging). Next, students
obtain the mass of the gummi bear by placing it into
the plastic cup and massing it using a balance. Ask
students why they need to obtain the mass of the
cup; this will determine if they understand that they
will need to subtract the mass of the plastic cup in
order to obtain the gummi bear’s mass. If sharing
equipment between groups, allow approximately 20
minutes for all measurements to be obtained. Next,
have students label the plastic cup with their name
using a permanent marker and add 25 mL of water
to the cup containing the experimental bear. Note:
Tap water works well for this experiment, but for the
biggest change in volume, use distilled water.
The next day, students don their chemical splash
googles and obtain their experimental bear, which
soaked in water overnight. The bears have grown
many times in volume, so they are extremely fragile.
Students bring their cups containing bears to me. I
then use a household strainer (not a colander) to carefully strain the water out of the cup. A small strainer
makes it easier to handle the bear. In addition, the
small sizes of the holes in the strainer effectively capture any pieces of the bear that may break off during
the straining process. (Although there is little water
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Activity Worksheet: Gummi Bears
Question
What will happen to a gummi bear when you put it in
water overnight?
Prelab question
What information or prior experiences can you use to
make a prediction?
Record your prediction and state your reasoning.
Materials
• 3 oz., clear, plastic cup
• 1 Black Forest gummi candy bear (other brands
can be used; test first to make sure the bears
expand, not dissolve)
• centimeter ruler
• triple beam balance
• graduated cylinder
• 25 mL distilled or tap water
• permanent marker
• strainer
• 2 paper towels
• chemical splash goggles
• small plastic cups
on the outside of the bear, some water usually remains
in the cup. This water could be strained into a beaker
for measuring if you wish to have students calculate
the total amount of water absorbed.) I hand the cup
with the bear back to the student with instructions not
to eat the bear, but to recalculate the volume and mass
of the bear using the same procedures from the prior
day. I also hand students a control bear (a new gummi
bear), which provides a good visual for comparison. If
you have a digital camera available and students will
be writing a formal lab report, you can have them take
a picture of a control bear adjacent to a soaked bear
for the report. Direct students to answer the analysis
questions on their Activity Worksheet, which focus on
calculating change in mass and volume. Students can
then compare their original prediction to what actually
occurred. I ask students to explain what happened
to the gummi bear; students struggle with the idea
that water diffused into the gummi. When we discuss
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Safety note: Wear chemical splash goggles during this
lab activity. Do not eat gummi bears. Wash your hands
and work area when done.
Procedure
Gummi bear volume
1. Label your plastic cup with your table name and class
period.
2. Use the ruler to find the length of your gummi bear.
Measure from the top of the bear’s head to the bottom
of its feet to the nearest 0.1 cm. Record in the data
table below.
3. Measure the width of your gummi bear at the widest
point across the back of the bear to the nearest 0.1
cm. Record in the data table below.
4. Measure the height of your gummi bear by lying it on
its back and measuring from the heel of the foot to
the tip of the toes to the nearest 0.1 cm. Record in the
data table below.
5. Calculate the approximate volume of the bear by
multiplying length x width x height (L x W x H). Round
to the nearest 0.01 cm and record in the data table
below.
of the cup to find the mass of the gummi bear.
Record in the data table below.
3. Add 25 mL of water to the cup and allow to sit
overnight.
4. On Day 2, have the teacher strain the gummi bear
from the water. Place the gummi bear on a paper
towel.
5. Dry the inside of the plastic cup.
6. Fill out the data table below.
Analysis questions
1. How did the volume change? Be sure to discuss
the before and after soaking data in your response.
2. Use math to determine the change in volume to
the bear after soaking. Show your work.
3. How do you think your results would change if
you were to calculate volume using the water
displacement method?
4. How did the mass change?
5. Use math to determine the bear’s change in mass
after soaking. Show your work.
6. How do the results compare to your prediction?
Gummi bear mass
1. Find the mass of your plastic cup.
7. Why do you think the bear reacted to the water the
way it did?
2. Place the bear in the plastic cup. Find the mass of the
gummi bear and cup. Remember to subtract the mass
8. Predict how the gummi bear would react to being
submerged in other liquids.
Data table of gummi bear measurements before and after soaking in water
Descriptive observations
Length
in cm
Width
in cm
Height
in cm
Approximate
volume
(L x W x H)
Mass of
gummi bear
in grams
Before
soaking
After
soaking
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diffusion later in the school year, however, the ability
to refer to the gummi bear as a concrete example of
diffusion is extremely helpful for developing student
understanding of molecular movement. The analogy
of the bear being like a sponge that soaks up water
is one that helps students understand the difference
between absorbing and dissolving. (For additional
information on this topic, see “Osmosis and Diffusion
Through a Semipermeable Membrane” on page 77
of this issue.)
Students can graph any number of pieces of data,
either by hand or using a spreadsheet program, including the before and after mass and volume or the
percentage change in mass and volume. I have found
that for advanced students who possess solid math
skills, calculating the percentage change in mass
and volume is a good challenge (the control bear
would be the standard). Another extension is to have
each student enter his or her data into a classroom
spreadsheet to obtain the average change in mass
and volume. This lends itself to a good discussion of
the importance of repeating an experiment numerous
times for validity.
For students to conduct inquir y, they must move
beyond process skills. This lab is also a great jumping-off point for students to develop their own inquiry
question. Students are amazed at the change in the
bear and often begin making additional observations
and predictions as they examine each other’s gummi
bears. The teacher can ask questions such as “Do
all gummi bear colors absorb the same amount of
water?” “Do gummi worms or Swedish fish react
in the same way as gummi bears?” “Does placing
the cup into the refrigerator affect the amount of
water absorbed?” and “How does a gummi bear
react when soaked in liquids such as tea or soda?”
These questions will help students generate their
own investigable question that can be conducted
easily at home with gummi bears and a centimeter
ruler. Students should be encouraged to perform
multiple trials of their experiment for validity. You
can also have students collaborate in teams to develop a follow-up experiment that can be conducted
in class. This is a great way to facilitate conversation
among students when they are making predictions
regarding the outcome of their experiment. This
experiment could also be used as an introduction
to diffusion; the bear swells with the absorption of
water as the water moves from an area of high con-
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centration to low concentration. You can conduct a
similar activity using a synthetic product made from
water-absorbing polymers. Relatively inexpensive,
reusable animal-shaped polymers that are capable
of growing many times when submerged in water
can be purchased through science supply stores.
Assessment
The week after the activity, I administer a lab practical
that requires students to individually mass and measure a variety of common classroom objects such as
paper clips, stoppers, and 3 × 5 cards. Students can
also be assessed on their ability to use the lab results
to properly construct a graph, for thoughtful responses to analysis questions, and on their ability to design
and carry out a subsequent experiment in which they
change a variable and compare the resulting mass
and volume to a control bear. n
References
Ash, D. 2001. The process skills of inquiry. In Foundations:
A monograph for professionals in science, mathematics,
and technology education: Inquiry—Thoughts, views, and
strategies for the K–5 classroom, 51–62. Arlington, VA:
National Science Foundation. www.nsf.gov/publications/
pub_summ.jsp?ods_key=nsf99148.
Bellis, M. The history of gummi candy. http://inventors.
about.com/od/gstartinventions/a/gummi.htm.
Center for Science, Mathematics, and Engineering Education (CSMEE). 2000. Inquiry and the National Science
Education Standards: A guide for teaching and learning.
Washington, DC: National Academies Press.
Gelatin Innovations. 2009. Did you know? www.
gelatininnovations.com/pages/what_is_gelatin.html.
Padilla, M.J. 1990. The science process skills. Research
matters—to the science teacher. Reston, VA: National Association for Research in Science Teaching. www.narst.
org/publications/research/skill.cfm.
Resources
Gummy bear song—www.youtube.com/
watch?v=astISOttCQ0
Patty McGinnis (pmcginnis@methacton.org) is
a science teacher and gifted support specialist
at Arcola Intermediate School in Norristown,
Pennsylvania.