Teaching the Concept of Half-Life
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Teaching the Concept of Half-Life . Lesson Sequence. Lesson 1: Radioactive Decay Bohr-Rutherford model of atom, isotopes – review Alpha, Beta and Gamma Decay Lesson 2: Measuring the rate of Radioactive Decay Process Half-Life Aplication of Half-Life: Carbon Dating

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Teaching the Concept of Half-Life

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Teaching the Concept of Half-Life

Lesson Sequence

Lesson 1: Radioactive Decay

  • Bohr-Rutherford model of atom, isotopes – review

  • Alpha, Beta and Gamma Decay

    Lesson 2: Measuring the rate of Radioactive Decay Process

  • Half-Life

  • Aplication of Half-Life: Carbon Dating

    Lesson 3: Nuclear Fission and Nuclear Power Generation

  • Mass Energy Equivalence

  • Nuclear Fuel

  • Chain Reactions

    Lesson 4: Nuclear Fusion

  • Nuclear Stability

  • Stellar Fusion

  • Magnetic Confinement Fusion

    Lesson 5: Applications of Nuclear Technology

  • Candu Reactors, Waste disposal

  • Medical applications of Radioisotopes

    Lesson 6: Nuclear Energy : Benefits and Hazards

  • Curriculum Expectations for Energy and Society Unit


    D3. demonstrate an understanding of work, efficiency, power, gravitational potential energy, kineticenergy, nuclear energy, and thermal energy and its transfer (heat).


    D1.2 assess, on the basis of research, how technologiesrelated to nuclear, thermal, or geothermalenergy affect society and the environment (e.g., thermal regulating units, radiopharmaceuticals,dry-steam power plants, ground-source heatpumps) [IP, PR, AI, C]

    D2.1 use appropriate terminology related to energytransformations, including, but not limited to:mechanical energy, gravitational potential energy,kinetic energy, work, power, fission, fusion, heat, heatcapacity, temperature, and latent heat [C]

    D2.7 compare and contrast the input energy,useful output energy, and per cent efficiencyof selected energy generation methods(e.g., hydroelectric, thermal, geothermal, nuclearfission, nuclear fusion, wind, solar) [AI, C]

    D2.8 investigate the relationship between the conceptsof conservation of mass and conservationof energy, and solve problems using the mass–energy equivalence [PR, AI]

    D3.6 describe and compare nuclear fission andnuclear 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 alphaparticles, beta particles, and gamma rays

    D3.12 explain the energy transformations thatoccur within a nuclear power plant, with referenceto 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 electricalenergy 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

    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!

    • What is the risk from Caesium-137 and Iodine -131 at Fukushima?

    • How long does it take for radioactive atoms to decay?

    Specific Curriculum expectations for the lesson:

    • D3.11 explain radioactive half-life for a givenradioisotope, and describe its applications and their consequences

    Half- Life: Teaching Strategy 1: Inquiry Based Learning:

    • Virtual Lab: Measuring the Rate of Radioactive Decay


    • 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?

    • The average length of time it takes a radioactive material to decay to half of its original mass

    What is Half–Life?

    • 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:

    Half- Life: Teaching Strategy 2: Demonstration

    Students will participate in a demonstration that visually illustrates the concept of half-life

    • 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

    • 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

      • count the number of parent and daughter isotope atoms in each bag

      • determine how many half-lives the isotope has gone through

      • 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

    • 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

    Potential Student Difficulty

    Realizing the difference between radioactivity and radioactive decay


    Show your student the following poster and explain using pictures what the difference is

    Potential Student Difficulty


    Understanding that nuclei do not disappear when they decay

    Show students an animation


    Potential Student Difficulty


    Wrongly interpreting half-life as half the time for the radioactivity to disappear

    • 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

    • 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


      • 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

    • Assssment will be ongoing

    • Multiple intelligences will be taken into account while assessing students

    • Students will be assessed based on:

      • 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

    • 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

    Suggestions for other student labs/activities related to nucelar reactions

    • Virtual Lab on radioactive decay (alpha decay)

    • http://phet.colorado.edu/en/simulation/alpha-decay

    • Radioactive Dating: Looking at Half-Lives UsingM&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:



    • Demonstration of radioactive decay using pennies


    • Radiometric Dating Activity


    • Information about half-life - half-lives for various radioisotopes:


    • 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. NelsonThompson Learning

    • Ontario Science Curriculum Grades 11-12



    • Virtual Lab: Measuring the Rate of Radioactive Decay


    • Worksheet on Half- Life


    • Radioactive Decay – picture:


    • Radioactivity -definition and picture:


    • Half-Life – picture on the main site:


    • Explaining Radioactivity



    • Carbon Dating:


    • Carbon 14 Decay


    • Using Popcorn to Simulate Radioactive Decay


    • Half-Life Graph:


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