# Learning Exercise

## Radioactive Decay Lesson

Next, a lab will model the rate of decay of radioactive isotopes using a penny model. Students will work in groups to complete the lab and then present their findings to the class on a white board.

Students will be given a short quiz on the events in the lesson which will be used for individual assessment.

**Course:**Nuclear Processes

Halfway down the web page is a wonderful applet depicting Radioactive Decay. see more

#### Exercise

1) After bell Rings, lights go off, video plays:

http://www.jpl.nasa.gov/videos/mars/viking-062206/viking-062206.mp4

Announce beginning of Nuclear Processes unit, Talk about energy briefly and

place the two-question prompt on the over head.

(questions should be generic math problems that are relevant to half life

concept e.g what is half of half of half of half of 800?)

Students: Will be attempting to solve the two items on the overhead and asking

questions

Teacher: taking role, answering questions, reviewing answers when the students

have finished with the two questions, finally announcing the outline of the days

events.

2) PowerPoint and Web demonstration of radioactive decay

Students: actively listening to the web demo and asking question as well as

answering them

Teacher: Making transition from the two-question prompt to the lecture, and

explaining how decay half life proceeds with time

3) Lecture on radioactive decay

(should be specific to your class's achievement level - include vocabulary and

definitions, possibly alpha, beta, and gamma radiation and even decay equations

for an advanced audience)

Students: Taking notes in composition book, asking questions.

Teacher: presenting new material, monitoring students for participation and

attention.

4) Lab instructions/ pass out group hand outs

Students: Receiving hand-out and asking lab questions if confused

Teacher: Providing instruction on the lab, asking for questions, putting

students in groups, moving seats to such that they are conducive to group work,

assigning tasks for group members.

5) Penny lab

Students: Working in groups on the penny lab

Teacher: monitoring the students, asking questions about the lab to students,

keeping them involved.

6) Group presentations

Students: Showing their graph and presenting their ideas and/or solution to an

assigned problem

Teacher: giving positive feedback, offering encouragement, using the

presentation to facilitatereview of the material.

7) Final assessment quiz (please tailor the quiz to your students - rewrite if

necessary)

Students: going back to their seats, and taking the quiz

Teacher: quietly observing

Radioactive Decay Quiz

Each question is ½ point

Part 1 Instructions: fill in the blank with the best fitting term from todays

lesson.

1. The time required for one-half of a radioactive isotope to decay into its

products is _______________.

2. A series of nuclear reactions that begins with an unstable nucleus and

results in the formation of a stable nucleus is _______________.

3. A radioactive isotope is also known as an unstable ____________ atom.

4. The final decayed atom is called the stable _____________ atom.

Part 2 Instructions: Solve each question. Please show your work.

5. If a sample of radioactive isotope had half of its atoms decay in 200 years,

how long would it take for 100 atoms of the same radioactive isotope to decay to

25 atoms? Show work

6. A sample of 800 Carbon-14 atoms, a radioactive isotope, has decayed to 200

atoms over a given period of time. If each time a half-life occurs ½ of the

atoms decay, how many half-life periods have occurred?

7. What is the half life of carbon-14 if it took 17,190 years for 800 atoms to

decay to 200 atoms?

8. A Radioactive isotope has a half life of 10 seconds. How many atoms will

remain after 40 seconds of a sample of 400 atoms?

#### Disciplines

#### Audience

#### Technical Notes

Overhead projector

Transparencies

Dry erase markers

White boards

Web connected classroom

http://www.walter-fendt.de/ph14e/lawdecay.htm

http://www2.jpl.nasa.gov/galileo/messenger/oldmess/2RTG.html

Differentiated Instruction:

This lesson has been designed from the perspective of my students, including English language learners, to best suit the members of my classroom (SDAIE strategy 1). I will utilize different modes of instruction to try to reach all students in the classroom. There will be a laboratory, an individual assignment, a group assignment, a presentation, and (SDAIE strategy 4) oral as well as written instruction with this activity. The lecture incorporates an internet site that show good graphical representation of decay for my visually inclined learners. I will be careful to watch my pace and use student reaction as a guide for my pace while teaching (SDAIE strategy 10).

These strategies will benefit my entire student population and will aid them in there efforts to meet of surpass the standards addressed in the lesson.

#### Topics

Chemistry, 9-12, Nuclear Processes

Concept 11: Nuclear processes are those in which an atomic nucleus changes, including radioactive decay of naturally occurring and human-made isotopes, nuclear fission, and nuclear fusion. As a basis for understanding this concept:

Standard f: Students know how to calculate the amount of a radioactive substance remaining after an integral number of half lives have passed.

CA- CCTC Level II Technology Standards

Standard 16: Using Technology to Support Student Learning

Element: 16(a) Each participating teacher communicates through a variety of electronic media.

Element : 16(e) Each participating teacher uses technology in lessons to increase students ability to plan, locate, evaluate, select, and use information to solve problems and draw conclusions. He/she creates or makes use of learning environments that promote effective use of technology aligned with the curriculum inside the classroo

#### Type of Task

#### Learning Objectives

Students will be able to

1) Describe how radioactive isotopes decay with time

2) Calculate the amount of a radioactive substance remaining after an integral number of half lives have passed