Name: ________________________
Date: _____________________
Block: __________
Half Life Inquiry Lab Template
Criterion C Rubric
Experiment Title:
Wild Guess Question & Prediction: How long would it take a 5 kg sample of Pu-239 to decay until it is considered safe
(1/1032 or 0.1% of the original mass)?
I think a 5 kg sample of Pu-239 will take 35 years until it is considered safe because I know that radioactive elements
typically take a very long time to decay.
Research Question: How does the number of radioactive atoms depend on time for each isotope under study?
Hypothesis:
Graph form:
In words:
y-axis
1
I think the number of radioactive atoms depends
on time in an inverse relationship because
something that’s radioactive should always stay
radioactive. Over time, it will become less and
less radioactive, but the amount of radioactive
atoms will get lower until there’s no
measurement.
5
x-axis
5,0
Procedure:
1. Go to the Dice Decay Simulator Site
2. Go to line 31: add ( after the word print & add ) at the end of the line 31:
3. Check your code. If you hit, evaluate does it run?
4. Change line 2 from P = [50] to P = [100 or 200]
10,0
5. Verify line 5 has p=0.1 for I-131 or p=0.02 for Pu-239
6. Go to line 31. Before the word print add the following: if(rolls%5 > 3): for I-131 -OR- if(rolls%20 > 18): for Pu-239 &
hit enter. You cannot have any spaces in front of the if statement (red box) and the print line needs to be indented
as shown below (red arrow).
7. Hit the evaluate button. Enter the first five data points (roll number, remaining atoms) for your isotope into the
shared Google Sheet for your group and class.
8. To determine the actual time use this slide. For I-131, each roll will be 1 day. For Pu-239, each roll will be 650
years.
9. Graph the actual time and average number of atoms in your Desmos graph, choose the line of best fit and display
the equation on the chart.
Quantitative Data: Shared Quantitative Data Template
Graph (with Mathematical Model): Iodine Desmos Template or Plutonium Desmos Template
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Board Meeting Notes:
Insert notes from our board meeting here to help write your conclusion.
The relationship between time and the mount of radioactive atoms is called exponential decay or negative exponential
our k value for atoms that are the same is similar
Y intercept= atoms we start at
its not a inverse because it divides it by fours, eighths, etc as opposed to when x doubles, y halves.
When x doubles, y halves * how many times you’ve halved it
N = amount of radioactive left,
N0= starting amount
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reasoning discusses decay rate, how it affects graph
What do large decay rates tell you, what do small
when x doubles y halves at a halfing rate
Natural log of your answer is equal to the exponent, log base E, -logE
E = pi, always 2.71
^K = question mark, dependent on type of atom, 0.11 is their decay rate
t = time
Limitation is that we don’t reach zero mathematically but irl it does reach zero
Starting number of atoms is similar to N0, and the y intercept
starting number
Conclusion: The mathematical model that describes this relationship is….
Claim (What is the mathematical relationship between time and number of radioactive atoms? )
According to the data, our findings suggest that the mathematical relationship between time and number of radioactive
atoms is a negative exponential one.
The data bolsters this position because the evidence found through the process of our lab and the discovery of the
mathematical model shows the relationship between the data of the lab and helps us to universalize our findings.
Reasoning for Results (Use the decay rate (k) to explain how quickly or slowly I-131 & Pu-239 go through alpha & beta decay.)
Choose one of these sentence frames to get you started or create one of your own.
● If _________, then _________ because…
● If _________ results in _________, it follows that…
● Since I observed _________, _________, and _________ it leads me to believe that…
Prediction (How long will it take for the radioactive Pu-239 waste used at Hanford to become safe?)
Choose one of these sentence frames to get you started or create one of your own. 222830.8155 years
● I predict that ________________.
● Based on my data/the classes’ data , a logical forecast is __________.
● Experts consistently agree that _______________.
Half Life Inquiry Lab Template
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Confidence with Reasoning (How confident are
you in your prediction? Why?)
Choose one of these sentence frames to get you
started or create one of your own.
● I have __________ confidence because
________.
● The certainty of my prediction is
__________ due to the
__________________________.
● The sureness of my prediction is affected
by ____________ resulting in a
________ confidence.
Determining Confidence
Considerations
Predicted Value Within
the Data Range
The best-fit line is near the
center of nearly all the data
points.
High
M
Limitations: (Does the mathematical model always apply or are there situations
where
it breaks
down? Are there
The best fit
line goes
through
uncontrolled factors that may have affected your results? If so, how?) the error bars but not the data
Medium-High
Choose one of these sentence frames to get you started or create one of your own.points
● ___ applies when...
● The variation in ___ was influenced by …
There are data points that are
● ___ may have affected the results by …
far from my line of best fit on
my graph (outliers).
Medium
Actual Result (How long does the USDA say the waste will be radioactive? How does this compare to your prediction?)
Choose one of these sentence frames to get you started or create one of your own.
● _____ and _____ is similar and/or different because _____________.
● My prediction(s) were accurate for ________________ but was not expecting __________________.
● While _____ and _____ are both comparable because __________, there are several noticeable differences
between them such as _____________.
Extension/Application (What is a new testable question you have that extends the knowledge of this investigation? –ORWhat is a connection you can make between what you learned in this investigation to everyday life?)
Choose one of these sentence frames to get you started or create one of your own.
● Now I wonder ______________.
● Another question that I have now is ____________.
● When I saw __________, I didn’t know why it happened but now I realize it is because _________________.
● I now comprehend that when I observed _________ that it is caused by _______________.
Checklist:
● Claim includes mathematical model (exponential
decay)
● 1 piece of evidence using the equation
● 1 piece of evidence describing the shape of the
graph
● 1 piece of evidence using data points or explaining
constants
● Uses explanation of radioactive decay processes
(alpha/beta decay) in reasoning to explain why the
variables have this relationship
Half Life Inquiry Lab Template
Pred
t
● Confidence determined by using embedded table
● Limitation(s) determined for the experimental
setup or equation
● Comparison of prediction with article linked in
slides (actual result)
● Percent Error calculation (for 7/8 level)
● Propose a new research question to extend the
knowledge in this investigation -OR- explain how
this relationship applies to another real world
scenario.
5
M
● Prediction calculated by using the mathematical
model
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