LESSON 19: Puffed Rice Fleas
ESTIMATED TIME Setup: 5 minutes | Procedure: 5 minutes
• DESCRIPTION
• MATERIALS
Charge kernels of puffed rice cereal with static
electricity to explore the structure and interactions
of matter.
Plate
Puffed rice cereal
o Balloons
o Charging cloths (wool, plastic wrap, carpet, etc.)
o
o
• OBJECTIVE
This lesson introduces static electricity and the
structure of matter. Students witness the movement of
puffed rice cereal to and from a balloon after it has
been “charged.” The lesson can be extended to
address ions and electricity.
• CONTENT TOPICS
Scientific inquiry; properties of matter; atomic
structure; attractive forces (static electricity)
Always remember to use the appropriate safety
equipment when conducting your experiment.
Refer to the Safety First section in the Resource Guide
on pages 391–393 for more detailed information about
safety in the classroom.
Jump ahead to page 248 to view the
Experimental Procedure.
NATIONAL SCIENCE EDUCATION STANDARDS SUBJECT MATTER
This lesson applies both Dimension 1: Scientific and Engineering Practices and Dimension 2: Crosscutting Concepts
from “A Framework for K–12 Science Education,” established as a guide for the updated National Science Education
Standards. In addition, this lesson covers the following Disciplinary Core Ideas from that framework:
• PS1.A: Structure and Properties of Matter
• PS2.B: Types of Interactions
• ETS2.B: Influence of Engineering, Technology, and Science on Society and the Natural World
(see Analysis & Conclusion)
OBSERVATION & RESEARCH
BACKGROUND
All matter is made up of basic elements. Elements are pure
substances that cannot be broken down further by normal
chemical means. They are known as the building blocks of
matter. Elements are composed of atoms. The elemental
form of a substance is made up of only one type of atom.
An atom is the fundamental unit of an element; it is the
smallest particle of an element that retains the element’s
chemical properties. Atoms are made up of even smaller
parts—protons, neutrons, and electrons.
Protons and neutrons are held tightly together in the
nucleus, or core, of an atom, while electrons occupy the
space outside of the nucleus. Protons, neutrons, and
electrons have different characteristics, such as different
masses and electric charges. Protons have a positive
charge, neutrons have no electric charge, and electrons
are negatively charged. When the number of protons in
an atom equals the number of electrons, the positive and
negative charges are balanced. The atom is electrically
neutral. However, atoms can gain or lose electrons,
leaving them with a positive or a negative charge.
Likewise, larger objects can gain or lose electrons,
becoming positively or negatively charged. Static
electricity is the buildup of electric charges on the
surface of an object, which occurs when electrons are
pulled from the surface of one material and relocated
onto the surface of another material. Some materials,
such as glass, human hair, and nylon tend to give up
You Be TheLESSON
Chemist®Activity
Activity
Guide
Guides
| page 245
1:
Goofy
Putty
245
LESSON 19: Puffed Rice Fleas
electrons easily and become positively charged. Other
materials, such as silicon and polyester, tend to collect
electrons from other materials.
In addition, like charges repel one another, while
opposite charges attract one another. Therefore, a
positively charged object will attract a negatively
charged object, but two negatively charged objects
will repel one another. (Think of magnets!)
In the experiment, when students rub a balloon against a
charging cloth, the cloth easily gives up electrons to the
balloon. Because the balloon is collecting extra
electrons, it becomes negatively charged. When the
balloon is held near a relatively neutral object, such as
puffed rice cereal, the balloon will attract that object.
Although the puffed rice cereal is neutral, it has a
slightly positive charge compared to the balloon.
Because opposites attract, the puffed rice cereal will be
attracted to the balloon.
CONNECT TO THE YOU BE THE
CHEMIST CHALLENGE
For additional background information, please
review CEF’s Challenge study materials online at
http://www.chemed.org/ybtc/challenge/study.aspx.
• Additional information on elements, atoms, and
electrons can be found in the Atomic Structure
section of CEF’s Passport to Science Exploration:
The Core of Chemistry.
HYPOTHESIS
uPuffed rice cereal will move to and from a
balloon as a result of electric charges created
on different materials. When objects have opposite
electric charges they will attract, and when they
have similar charges, they will repel.
Eventually, some of the excess negative charge on the
surface of the balloon will move to the kernels of puffed
rice cereal, causing the kernels to become negatively
charged. The similar charges will repel each other,
causing the kernels to “jump” away from the balloon.
FORMULAS & EQUATIONS
Protons, neutrons, and electrons make up atoms. Protons
have a positive electric charge, neutrons are neutral, and
electrons have a negative electric charge. The charge of
an atom can be determined from the net (total) electric
charge of the protons and electrons. Therefore, if an
atom has two protons (a charge of +2) and two electrons
(a charge of -2), the total charge is zero (+2 + -2 = 0).
Fun Fact
Atoms and molecules are very
small. A piece of paper is about
1,000,000 atoms thick! Even when
several atoms are combined, the
resulting molecule is very,
You Be The Chemist® Activity Guide | page 246
very small.
LESSON 19: Puffed Rice Fleas
DIFFERENTIATION IN THE CLASSROOM
LOWER GRADE LEVELS/BEGINNERS
Perform the experiment as described on page 248, and
focus on the structure and properties of matter. Discuss
how matter is made up of particles that are too tiny to see;
however, we know those particles exist because of certain
properties and interactions. You can also use gases to help
explain how we know things exist that we can’t see.
HIGHER GRADE LEVELS/ADVANCED STUDENTS
DESCRIPTION
Charge kernels of puffed rice cereal with static electricity
to explore the structure and interactions of matter.
OBJECTIVE
This lesson introduces static electricity, the structure of
matter, and ions as students witness the movement of
puffed rice cereal to and from a balloon after it has been
“charged.”
OBSERVATION & RESEARCH
All elements, and therefore all matter, are composed of
atoms. An atom is the fundamental unit of an element;
it is the smallest particle of an element that retains the
element’s chemical properties. Atoms are made up of
even smaller parts—protons, neutrons, and electrons.
Protons and neutrons are held tightly together in the
nucleus, or core, of an atom, while electrons occupy the
space outside of the nucleus. Protons have a positive
charge, neutrons have no electric charge, and electrons
are negatively charged. When the number of protons in
an atom equals the number of electrons, the positive and
negative charges are balanced. The atom is electrically
a general term that includes a variety of occurrences
that result from the flow of electric charges. These
occurrences include lightning, the flow of electric
currents in wires, and static electricity.
Static electricity is the buildup of electric charges on the
surface of an object, which occurs when electrons are
pulled from the surface of one material and relocated
onto the surface of another material. Electrons can be
transferred from one object to another as a result of
chemical reactions, mechanical motion (such as rubbing),
or other means. In addition, like charges repel one
another, while opposite charges attract one another.
Therefore, a positively charged object will attract a
negatively charged object, but two negatively charged
objects will repel one another.
In the experiment, when students rub a balloon against a
charging cloth, the cloth easily gives up electrons to the
balloon. Because the balloon is collecting extra electrons,
it becomes negatively charged. When the balloon is held
near a relatively neutral object, such as puffed rice cereal,
the balloon will attract that object. Although the puffed
rice cereal is neutral, it has a slightly positive charge
compared to the balloon. Because opposites attract, the
puffed rice cereal will be attracted to the balloon.
Eventually, some of the excess negative charge on the
surface of the balloon will move to the kernels of puffed
rice cereal, causing the kernels to become negatively
charged. The similar charges will repel each other,
causing the kernels to “jump” away from the balloon.
neutral.
An ion is an atom or molecule that has lost or gained one
or more of its outer electrons. Therefore, ions have either
a positive or a negative charge. Because ions have an
overall electric charge, they interact with other charged
objects. A positive ion will attract negatively charged
objects, such as negatively charged ions or free electrons.
(Certain materials, such as metals, have loosely held
electrons that move freely through the material.)
Likewise, negative ions will attract positively charged
objects.
CONNECT TO THE YOU BE THE
CHEMIST CHALLENGE
For additional background information, please
review CEF’s Challenge study materials online at
http://www.chemed.org/ybtc/challenge/study.aspx.
• Additional information on elements, atoms,
electrons, and ions can be found in the Atomic
Structure section of CEF’s Passport to Science
Exploration: The Core of Chemistry.
Larger objects can gain or lose electrons, becoming
positively or negatively charged. Electricity is
You Be The Chemist® Activity Guide | page 247
LESSON 19: Puffed Rice Fleas
EXPERIMENTATION
As the students perform the experiment, challenge them to
identify the independent, dependent, and controlled
variables, as well as whether there is a control setup for the
experiment. (Hint: If a noncharged object is moved toward
the puffed rice cereal, will it behave differently?) Review
the information in the Scientific Inquiry section on pages
14–16 to discuss variables.
NOTES
EXPERIMENTAL PROCEDURE
1. Sprinkle several kernels of puffed rice cereal on
a plate.
2. Rub an inflated balloon over a charging cloth in
one direction to create static electricity.
3. Slowly, bring the charged balloon near the
puffed rice cereal. The kernels of puffed rice
cereal will “jump” off the plate and adhere to the
surface of the balloon.
4. Hold the balloon motionless. Some of the kernels
will repel from the balloon.
5. Try rotating the balloon immediately after
collecting several kernels of puffed rice cereal,
positioning the balloon so that the kernels of
puffed rice cereal are on top. Wait until the
kernels are repelled from the balloon. (This action
should dispel the notion that the puffed rice kernels
are merely falling off the balloon rather than being
repelled from it.)
DATA COLLECTION
Have students record data in their science notebooks or
on the following activity sheet. What happens after you
rub the balloon against a charging cloth? How does the
puffed rice cereal behave in relation to the balloon?
Have students answer the questions on the activity sheet
(or a similar ones of your own) to guide the process.
You Be The Chemist® Activity Guide | page 248
LESSON 19: Puffed Rice Fleas
ANALYSIS & CONCLUSION
Use the questions from the activity sheet or your own
questions to discuss the experimental data. Ask students
to determine whether they should accept or reject their
hypotheses. Review the information in the Scientific
Inquiry section on pages 14–16 to discuss valid and
invalid hypotheses.
ASSESSMENT/GOALS
Upon completion of this lesson, students should be able
to …
• Apply a scientific inquiry process and perform an
experiment.
• Define atoms and describe the basic composition
of an atom.
• Differentiate between protons, neutrons, and
electrons.
• Explain electric charges and static electricity.
• Understand that “opposites attract” and “like
charges repel.”
REAL-WORLD APPLICATIONS
• If you rub your shoes on a carpet, your body may
collect extra electrons. These electrons will remain
on your body until they can be released. When you
touch certain objects, you will feel a shock, which is
simply a release of excess electrons.
• Long before GPS (global positioning systems) and
other high-tech navigational aids, the compass
provided humans with an easy way to determine
direction. A compass is composed of a magnet,
which is attracted toward the North Pole. The magnet
interacts with the earth’s magnetic field and aligns
itself to point to the magnetic poles. These directions
are called magnetic north and magnetic south. If you
turn the compass toward the South Pole, the needle
will repel from the South Pole and turn back to face
the North Pole.
COMMUNICATION
Discuss the results as a class and review the activity sheet.
Review the information in the Scientific Inquiry section on
pages 14–16 to discuss the importance of communication
to scientific progress.
• Define ions and describe the attraction of ions to
other electrically charged particles or substances
(see Differentiation in the Classroom).
MODIFICATIONS/EXTENSIONS
Modifications and extensions provide alternative methods
for performing the lesson or similar lessons. They also
introduce ways to expand on the content topics presented
and think beyond those topics. Use the following
examples or have a discussion to generate other ideas
as a class.
• Ask students if they have experienced static electricity
from clothing or blankets. Discuss what materials seem
to generate the greatest electric charges, and test
students’ predictions by using different materials to
charge the balloon. Likewise, move the charged
balloon toward different materials, such as small pieces
of aluminum foil or rubber bands, to determine
whether those substances behave differently than the
puffed rice. Discuss the results.
You Be The Chemist® Activity Guide | page 249
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
OBSERVE & RESEARCH
1. Write down the materials you see. ____________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
2. How might these materials be used? __________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Example (write or add image)
Element
Atom
Proton
Neutron
Electron
Electrically neutral
Static electricity
4. Consider how the puffed rice cereal will react to an electrically charged balloon and why.
uWrite your hypothesis. ______________________________________________________________
______________________________________________________________________________________
______________________________________________________________________________________
You Be The Chemist® Activity Guide | page 250
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
PERFORM YOUR EXPERIMENT
1. Sprinkle several kernels of puffed rice cereal on a plate.
2. Rub an inflated balloon on the carpet or wool material to charge the balloon.
3. Slowly, bring the charged balloon near the puffed rice cereal. Watch what happens.
4. Now, hold the balloon motionless. Watch what happens.
ANALYZE & CONCLUDE
1. What happens when you rub the inflated balloon on the carpet or wool material? (Can you see a change?)
______________________________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
2. What happens when you bring the charged balloon toward the puffed rice cereal? Why? ________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. What happens when you hold the balloon motionless for a while after the kernels of puffed rice cereal collect on the
balloon? Why? ______________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
4. What will happen if you place the balloon near the puffed rice cereal without rubbing it on something first? Why?
______________________________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
5. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist®Activity
ActivityGuides
Guide | page 251
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
EXPAND YOUR KNOWLEDGE—ADVANCED
1. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Example (write or add image)
Ion
Electricity
2. Have you ever experienced static electricity? If so, when? If not, can you give an example of static electricity?
______________________________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. Static electricity would occur most in what type of climate? Why? __________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 252
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
OBSERVE & RESEARCH
A plate, puffed rice cereal, balloons, a charging cloth …
1. Write down the materials you see. ____________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
A plate may be used to hold various substances. Puffed rice cereal may be eaten for breakfast.
2. How might these materials be used? __________________________________________________________________
Balloons may be used as decorations. A cloth may be used to clean. Together, these materials may be used to observe the effects of static
______________________________________________________________________________________________________
electricity.
______________________________________________________________________________________________________
3. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Element
A pure substance that cannot be broken down into
simpler substances by ordinary chemical or physical
means; an element is made up of only one type of
atom.
Atom
The fundamental unit of an element; the smallest
particle of an element that maintains the chemical
properties of that element.
Proton
A subatomic particle that carries a positive charge
and is found in the nucleus of an atom.
Neutron
A subatomic particle that carries no electric charge
and is found in the nucleus of an atom.
Electron
A subatomic particle that carries a negative charge
and occupies the space outside the nucleus of an
atom.
Electrically neutral
An atomic state in which the number of protons in
an atom equals the number of electrons, thus the
positive and negative charges are balanced.
Static electricity
The buildup of electric charges on the surface of an
object, which occurs when electrons are pulled
from the surface of one material and relocated
onto the surface of another material.
Example (write or add image)
4. Consider how the puffed rice cereal will react to an electrically charged balloon and why.
Puffed rice cereal will appear to jump to and from the balloon as a result of static
uWrite your hypothesis. ______________________________________________________________
electricity (the movement of electric charges between materials and the interactions between different charges).
______________________________________________________________________________________
______________________________________________________________________________________
You Be The Chemist® Activity Guide | page 253
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
PERFORM YOUR EXPERIMENT
1. Sprinkle several kernels of puffed rice cereal on a plate.
2. Rub an inflated balloon on the carpet or wool material to charge the balloon.
3. Slowly, bring the charged balloon near the puffed rice cereal. Watch what happens.
4. Now, hold the balloon motionless. Watch what happens.
ANALYZE & CONCLUDE
1. What happens when you rub the inflated balloon on the carpet or wool material? (Can you see a change?)
Rubbing the balloon on the carpet or wool material transfers electrons (negative electric charges) to the balloon. You cannot actually see this
______________________________________________________________________________________________________
change occur until the balloon comes in contact with other materials.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
The electric charge on the suface
2. What happens when you bring the charged balloon toward the puffed rice cereal? Why? ________________________
of the balloon (negative charge) will attract the puffed rice cereal because it has a more positive charge. Opposite charges attract.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
3. What happens when you hold the balloon motionless for a while after the kernels of puffed rice cereal collect on the
The puffed rice cereal will eventually gather some of the excess electrons from the balloon. Then, the similar charges
balloon? Why? ______________________________________________________________________________________
between the puffed rice cereal and the balloon will repel each other, causing the kernels to “jump” from the balloon.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
4. What will happen if you place the balloon near the puffed rice cereal without rubbing it on something first? Why?
Nothing will happen if you do not rub the balloon on something first because both substances will remain electrically neutral.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
______________________________________________________________________________________________________
5. Is your hypothesis valid? Why or why not? If not, what would be your next steps? ____________________________
Answer 1: Valid because the data support my hypothesis.
______________________________________________________________________________________________________
Answer 2: Invalid because the data do not support my hypothesis. I would reject my hypothesis and could form a new one, such as …
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 254
LESSON 19 ACTIVITY SHEET: Puffed Rice Fleas
ANSWER KEY Below are suggested answers. Other answers may also be acceptable.
EXPAND YOUR KNOWLEDGE—ADVANCED
Have students complete this section if you used the advanced differentiation information, or challenge them to find the answers to these
questions at home and discuss how these terms relate to the experiment in class the next day.
1. Define the following key terms. Then, provide an example of each by writing the example or drawing/pasting an
image of the example.
Term
Definition
Ion
An atom or group of atoms that has lost or gained one or
more of its outer electrons; an ion will have either a positive
or a negative charge.
Electricity
A form of energy that results from the flow of charged
particles, such as electrons or ions.
Example (write or add image)
2. Have you ever experienced static electricity? If so, when? If not, can you give an example of static electricity?
Static electricity can result from dragging your feet across a carpet, rubbing two types of fabric together, or pulling a fleece sweatshirt
______________________________________________________________________________________________________
over your head (and hair!). The friction between the two substances causes a buildup of electric charges on one substance.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
Static electricity would occur most in dry climates
3. Static electricity would occur most in what type of climate? Why? __________________________________________
because electrons stay on surfaces longer in dry air. Moist air conducts electricity better than dry air, so charges wear off quickly.
______________________________________________________________________________________________________
______________________________________________________________________________________________________
You Be The Chemist® Activity Guide | page 255