Today:

Friday: Discussion answering the question:
 “Is


radiation bad?”
Read and annotate 3 articles based on your
stakeholder.
Read and annotate 2 articles based on another that
you might be interested in.
Stakeholders

Strawberry farmer who irradiates
crops

Physician who treats radiation
poisoning

Flight attendant

Dental patient getting x-ray

Granite quarry worker

Soldier on a nuclear submarine

Concerned granite countertop
owner

Concerned consumer of bananas,
carrots, lima beans, and brazil nuts

Colorado resident concerned about 
altitude

Airline passenger

Wyoming resident concerned about 
Radon

X-ray technician

Hiroshima survivor

Concerned dental patient

Cancer patient about to undergo
radiation therapy

Environmentalist who wants more
nuclear power plants
Astronaut
Fukushima nuclear power plant
employee
Questions to answer?








What source of radiation are you being exposed to?
What type of radiation are you being exposed
to/emitting?
How dangerous is the extra radiation to you?
How much radiation are you getting?
How much would hurt you?
How much are other people getting at the same time or
because of you?
What kind of decisions should you be making when
regarding radiation?
Other talking points? Safety precautions?
Discussion Prep

List of Talking Points from a given perspective
(maybe you’re a farmer who irradiates crops)
2
sources at least:
 can
use EPA website from Radiation in Our Lives Worksheet
 One source should be to learn more about your particular
perspective (ex: what is crop irradiation? How does it affect
people? What are controversies surrounding it?)

Will also have Radiation in Our Lives WS with you
 Print
that out today, ALONG with your work cited
and information bullets for you tomorrow.
Class Discussion

Please have out:
 Rubric
 Webquest
 Article

notes
Line up at the back of the classroom.
Discussion Follow-Up – 10 min-ish
(Get out Loose Paper…under doc cam if you need it)



On a loose piece of paper, write a minimum of one paragraph
reflecting on what you’ve learned through the process. Make it
more interesting than: “I learned that radiation is bad.” I
want to know what new nuanced understandings about this
major issue you will take into the world with you. You may
include information you learned earlier or through the process
of this research. In summary, what has the process of doing
this research and having this discussion taught you?
Should be on ~p.98
When finished: Take some time to organize your science
journal. Tape all assignments in, make sure that each assignment
is on the correct page and update your T.O.C. at the front.
Parent Decay  Daughter Formation Curve
120
% of Isotope
100
80
And so on…
Total
Start
# of
21Half-Lives
Half-Life
25
50Atoms
parents;
100
parents;
50daughters
daughters
075
remains
same
60
40
Average Mm Remaining
Average Daughter
20
0
0
1
2
3
4
5
6
7
# Half-lives
8
9
10
11
12
Mm Decay Curve
120
Started with
100 Mm
% Remaining
100
50 Mm after
1 Half-life
½ of original
80
60
Can Change #
Half-Lives to
actual time for
each isotope
25 Mm after
2 Half-life
½ of the half
40
And So On…
20
0
0
CarbonUranium-235
14
1
2
3
4
5
6
7
# Half-Lives
8
9
10
11
12
Radiometric Dating



Every radioactive isotope has a unique half-life
If you know the original amount of an isotope in a sample,
and the rate of decay (half-life), it is possible to determine
the age of that sample.
For C-14 dating, the object must have carbon in it.

Object must have died recently enough to still have carbon-14 in
it



(fossil fuels are too old…they don’t have carbon-14)
While plant/animal is alive, has same C-14 concentration as
atmosphere (because it is breathing). When it decays, doesn’t
replenish C-14 supply, so as C-14 decays, it is possible to date
age since death.
For U-238 dating,

The object must have uranium in it… you get the idea
Practice
If a sample contains an isotope with a half-life of 20,000
years, how old would the sample be if:
Hint:
 ½ the original isotope remain?
Always start by
 20,000 years
figuring out how
many half-lives
there were.


1/8 the original isotope remain?
 60,000 years
What percent of the sample would be left if the sample
was 40,000 years old?
 25%
(or ¼)
Radioactive dating game

Linked to my web page, or go to:
 https://phet.colorado.edu/en/simulation/radioactive-
dating-game