Teaching the Concept of Half-Life
Lesson Sequence
Lesson 1: Radioactive Decay
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Bohr-Rutherford model of atom, isotopes – review
Alpha, Beta and Gamma Decay
Lesson 2: Measuring the rate of Radioactive Decay Process
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Half-Life
Aplication of Half-Life: Carbon Dating
Lesson 3: Nuclear Fission and Nuclear Power Generation
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Mass Energy Equivalence
Nuclear Fuel
Chain Reactions
Lesson 4: Nuclear Fusion
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Nuclear Stability
Stellar Fusion
Magnetic Confinement Fusion
Lesson 5: Applications of Nuclear Technology
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Candu Reactors, Waste disposal
Medical applications of Radioisotopes
Lesson 6: Nuclear Energy : Benefits and Hazards
Curriculum Expectations for
Energy and Society Unit
Overall:
D3. demonstrate an understanding of work, efficiency, power, gravitational potential energy, kinetic energy, nuclear
energy, and thermal energy and its transfer (heat).
Specific:
D1.2 assess, on the basis of research, how technologies related to nuclear, thermal, or geothermal energy affect society and
the environment (e.g., thermal regulating units, radiopharmaceuticals, dry-steam power plants, ground-source heat
pumps) [IP, PR, AI, C]
D2.1 use appropriate terminology related to energy transformations, including, but not limited to: mechanical energy,
gravitational potential energy, kinetic energy, work, power, fission, fusion, heat, heat capacity, temperature, and latent heat [C]
D2.7 compare and contrast the input energy, useful output energy, and per cent efficiency of selected energy generation
methods (e.g., hydroelectric, thermal, geothermal, nuclear fission, nuclear fusion, wind, solar) [AI, C]
D2.8 investigate the relationship between the concepts of conservation of mass and conservation of energy, and solve
problems using the mass– energy equivalence [PR, AI]
D3.6 describe and compare nuclear fission and nuclear fusion
D3.9 identify and describe the structure of common nuclear isotopes (e.g., hydrogen, deuterium, tritium)
D3.10 compare the characteristics of (e.g., mass, charge, speed, penetrating power, ionizing ability) and safety precautions
related to alpha particles, beta particles, and gamma rays
D3.12 explain the energy transformations that occur within a nuclear power plant, with reference to the laws of
thermodynamics (e.g. nuclear fission results in the liberation of energy, which is converted into thermal energy; the
thermal energy is converted into electrical energy and waste heat, using a steam turbine)
Introduction to Half-Life
After the earthquake and tsunami hit
Japan and its nuclear plants in 2011, the
world held its breath
• What is the risk from Caesium137 and Iodine -131 at Fukushima?
• How long does it take for
radioactive atoms to decay?
These headlines were almost in all
newspapers and television stations
Do you know how to measure
the rate of radioactive decay of
radiocative elements?
My guess is you do not.
Let us learn today how to do it!
Specific Curriculum expectations for the lesson:
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D3.11 explain radioactive half-life for a given radioisotope, and
describe its applications and their consequences
Half- Life: Teaching Strategy 1:
Inquiry Based Learning:
Virtual Lab: Measuring the Rate of Radioactive Decay
http://glencoe.mcgraw-hill.com/sites/dl/free/0078693896/280405/E18.html
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Students will use an inquiry based approach to investigate the meaning of
radioactive half-life
Students interactively learn that radioactive materials decay at different rates
What is Half–Life?
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The average length of time it takes a radioactive
material to decay to half of its original mass
What is Half–Life?
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The half-life of any given isotope is actually an average
time for a particular parent atom to decay to its
daughter atom
The larger the sample size, the more accurately a
material decays according to its half-life
Half-Life Equation:
A
A0
t
h
- mass
- initial sample mass
- time
– half-life
Half- Life: Teaching Strategy 2:
Demonstration
Students will participate in a demonstration that visually illustrates
the concept of half-life
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While standing, each of students will be flipping a
penny
Each time they flip, one half-life will have passed
If a penny lands on heads, the student is regarded as
radioactive, has decayed and needs to sit
If a penny lands on tails, the student have not decayed
(remain standing)
After each half-life , a teacher should count students
who stand and plot data on a the overhead
Students will be asked to predict what will happen to
the numbers of remaining parent isotopes
Half-Life: Teaching Strategy 3:
Application of Half-Life: Introduction to Carbon
Dating –Videos and Discussion
Students will learn what carbon dating is and why Carbon -14 is a
useful isotope for dating fossils and other archeological objects
 Carbon 14 Decay: http://www.youtube.com/watch?v=81dWTeregEA
 Carbon Dating: http://www.youtube.com/watch?v=31P9pcPStg&feature=related
Short Dicussion: Student will share what they understood from these videos
Half-Life Teaching Strategy 4:
Radiometric dating activity – What is the age of the
fossil?
This hands-on activity allows students to gain a better understanding
of how scientists use isotopes to determine the age of fossils
and archeological objects
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Students will find out the age of five different
„fossils”
 a bag represents a fossil and beads inside the
bag –> atoms
Students need to :
 use half-life properties of isotopes to
determine the age of different fossils
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count the number of parent and daughter
isotope atoms in each bag
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determine how many half-lives the isotope
has gone through
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determine the age of the fossil
Potential Student
Difficulty
Understanding that radioactive
decay is a spontaneous process
that involves irreversible
transformation of one element
into another
Solution
 Show your students a demonstration
with popping popcorn
 Explain that when popcorn kernels are
poured into popcorn popper, it is
impossible to predict which kernel
pops first
 When they are removed from the
popper they are not kernels any more.
They have been transformed and
changed forever
Realizing the difference
between radioactivity and
radioactive decay
Potential Student
Difficulty
Solution
Show your student the following poster and explain using pictures what the difference is
Radioactivity
refers to the particles which are
emitted from nuclei as a result of
nuclear instability
Radioactive decay
the process by which a radioactive
atom’s nucleus breaks apart and
forms different atoms
Potential Student
Difficulty
Understanding that nuclei do
not disappear when they decay
Solution
Show students an animation
http://www.youtube.com/watch?v=o-9yt7OAYmE
Potential Student
Difficulty
Wrongly interpreting
half-life as half the
time for the
radioactivity to
disappear
Solution
Use demonstrations such as
a coin toss or M&M’s to help
students understand the
concept
Depict the results of these
demonstrations as a curve of
an exponential decay
function
Analyze with student the
shape and changes in
number of isotopes
Safety Considerations
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Major safety concern should be an appropriate Internet
conduct as the virtual lab is done on-line
Enough space in the classroom should be provided for
students when they do their radiometric dating activity
The classroom should be free from clutter when students
circulate between stations while doing radiometric dating
activity
Practical Applications of Radioactive Decay
• MEDICINE
diagnostic medical imaging to detect tumors, bone fracture (medical and
dental X-ray images, SPECT, PET, MRI)
radionuclide therapy (RNT – bombarding dividing harmful cell with
radiation)
• EARTH SCIENCES – using C-14 for dating of geological specimens
• NUCLEAR PHYSICS – nuclear energy production
Differentiated Assesment
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Assssment will be ongoing
Multiple intelligences will be taken into account while assessing
students
Students will be assessed based on:
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Written laboratory reports (formative and summative)
Classroom discussions / small group discussions
Oral responses and presentations
Tests/ quizzes
Problem solving assignments (numerical and non-numerical)
Research assignments on applications of nucelar technology - students will be given
a chance to choose a topic and a method they would like to prepare the concept:
poster, newspaper article, song, Power Point Presentation, drama, podcast, game,
photo journal, demonstration, jigsaw, oral presentation
Exit tickets will be taken to check students’ understanding of delivered material
Keeping in mind a lesson on Half-Life- assessment will be based on:
written lab report (formative) and classroom discussion
Accomodations for students with special
needs
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Students with IEP
Activities, assignments, laboratory practice, tests, quizzes will be
modified and designed to meet specific learning needs
ELL students
Will be given more time to finish their assignments
Will be provided with teacher assistance whenever possible
Will be given a chance to seat beside someone who speaks their
first language/ who speaks English but is eager to provide
support
Students will receive (in advance) a lesson outline with important
words essential to do a classroom activity, lab reports
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Virtual Lab on radioactive decay (alpha decay)
http://phet.colorado.edu/en/simulation/alpha-decay
Radioactive Dating: Looking at Half-Lives Using M&Ms
http://serc.carleton.edu/sp/mnstep/activities/34884.html
Using Popcorn to Simulate Radioactive Decay
http://serc.carleton.edu/quantskills/activities/popcorn.html
Activities for teaching fundamental concepts of nuclear energy and
related topics (a variety of activities)
http://www.uraweb.org/reports/skoog.pdf
Radioactive Dating Game:
http://phet.colorado.edu/en/simulation/radioactive-dating-game
Nuclear Fission Simulation:
http://phet.colorado.edu/en/simulation/nuclear-fission
Class as an Artifact: A Radioisotope Dating Activity:
http://www.acad.carleton.edu/curricular/BIOL/classes/bio302/pages/ClassFossil.html
Students misconceptions:
http://www.furryelephant.com/content/radioactivity/teaching-learning/radioactivity-misconceptions/
http://serc.carleton.edu/quantskills/methods/quantlit/RadDecay.html
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Demonstration of radioactive decay using pennies
http://serc.carleton.edu/quantskills/activities/PennyDecay.html
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Radiometric Dating Activity
http://www.acad.carleton.edu/curricular/BIOL/classes/bio302/pages/half-life.html
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Information about half-life - half-lives for various radioisotopes:
http://theenergylibrary.com/node/11798
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Physics 11 - textbook – definition and explanation of half-life, definition of radioactive decay
DiGiuseppe M., Howes Ch. , Speijer J., Stewart Ch., Bemmel H. , Vucic R., Wraight V. Physics 11. Nelson
Thompson Learning
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Ontario Science Curriculum Grades 11-12
http://www.edu.gov.on.ca/eng/curriculum/secondary/2009science11_12.pdf
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Virtual Lab: Measuring the Rate of Radioactive Decay
http://glencoe.mcgraw-hill.com/sites/dl/free/0078693896/280405/E18.html
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Worksheet on Half- Life
http://mysite.cherokee.k12.ga.us/personal/brenda_priest/site/Subject%202%20Notes/1/Virtual%
20Half%20Life%20Lab.pdf
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Radioactive Decay – picture:
http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/earth_origin_lecture.
html
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Radioactivity -definition and picture:
http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/radact.html
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Half-Life – picture on the main site:
http://hendrix2.uoregon.edu/~imamura/121/lecture-9/lecture-9.html
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Explaining Radioactivity
http://www.youtube.com/watch?v=o-9yt7OAYmE
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Carbon Dating:
http://www.youtube.com/watch?v=31P9pcPStg&feature=related
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Carbon 14 Decay
http://www.youtube.com/watch?v=81dWTeregEA
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Using Popcorn to Simulate Radioactive Decay
http://serc.carleton.edu/quantskills/activities/popcorn.html
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Half-Life Graph:
http://web.princeton.edu/sites/ehs/osradtraining/radiationproperties/radiationproperties.htm
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