Unit 1 Task: The Undoing of -7, Whodunit?
Name: ____________________
Standards - MCC7.NS.1 Apply and extend previous understandings of addition and subtraction to add and subtract rational
numbers; represent addition and subtraction on a horizontal or vertical number line diagram.
a Describe situations in which opposite quantities combine to make 0.
b Understand 𝑝 + 𝑝 as the number located a distance |𝑝| from 𝑝, in the positive or negative direction depending on whether
𝑝 is positive or negative. Show that a number and its opposite have a sum of 0 (additive inverses). Interpret sums of
rational numbers by describing real-world contexts.
c Understand subtraction of rational numbers as adding the additive inverse, 𝑝 − 𝑝 = 𝑝 = (−𝑝). Show that the distance
between two rational numbers on the number line is the absolute value of their difference, and apply this principle in realworld contexts.
d Apply properties of operations as strategies to add and subtract rational numbers.
There has been a murder in the community of Pythagoras. While attending a family reunion, the victim
(-7) was murdered by family members. Witnesses claim there were two assailants. First, you are to
investigate the murder mystery as the Police Investigator and create wanted posters of the suspects.
Second, you are to trace the steps of the victim as the Forensic Expert and present your findings on a
number line along with a paragraph explaining what you believe happened to the victim on the night in
question. Next, you, in the role of the Funeral Director, are to write an obituary as a tribute to the great
life of (-7). Finally, you are to draw a map of the cemetery on a coordinate grid and as the Grave Digger
plot all the possible resting places for (-7).
ROLE
AUDIENCE
FORMAT
TOPIC
Police Investigator
(-7)'s Family
Wanted Poster
Integer
Forensic Expert
CSI Team
Case Study
Whodunit
Funeral Director
Newspaper Readers
Obituary
Integers
Grave Digger
Plot Committee
Map (-7)'s grave
Plotting Points
Role 1-Police Investigator: Your goal as a police investigator is to interview family members and obtain
composite sketches of the suspects to put on a wanted poster.
The only two clues that the police actually know is that the unfortunate event was committed by two
people, and that they were related to (-7). Your assignment is to interview the family of (-7) in order to
narrow down the suspect list. The family consists of two numbers who can be added together to make
(-7). All family members are currently considered suspects as (-7) was at a family reunion at the time of
the unfortunate event.
Please make a list of at least 10 relatives of (-7) and describe how you know that they are related.
Two family suspects related to (-7) are the Meter brothers. The brothers’ names are -10 Meter and +3
Meter. I know these brothers are related because when you add them together, they add up to (-7).
Draw wanted posters to notify people to be on the lookout for the list of possible suspects. The
community of Pythagoras is very nervous and wants the perpetrator caught immediately. Please include a
reward, a picture, and a description of each suspect. You can draw different wanted posters for the
different pairs of subjects.
Role 2-Forensic Expert: Your goal as a forensic expert is to retrace the steps of (-7) for the night of the
unfortunate event. For each stop, you will draw a symbol to represent where he stopped, trace the trail in
the appropriate color, and write down the mathematical equation that represents how many steps were
taken between stops.
Draw a number line and retrace the steps of (-7). This will also act as your map of Pythagoras.
According to witnesses, these were his steps on the night of the unfortunate event.

Negative Seven lives at (-7) Geometry Lane (draw a symbol at -7)

He left his house and went to visit (-2) to borrow some cinnamon for a tessellation tart recipe he
wanted to bring to the reunion. How many steps did he have to take to get to -2's house? _____
Write an equation to show the distance he traveled. _____________ Color this part of the number
line yellow for this part of the journey, and draw a symbol at -2.

According to (-2), while (-7) was standing on the doorstep with cinnamon in hand, he spied Mr.
Positive Eight’s dog sniffing around the fire hydrant at +1 Street. He ran from (-2)’s house,
cinnamon trailing behind him to catch the little dog. After all, he needs to be nice to Positive Eight
as he is his boss at the Metric Factory. (-7) could really use a promotion. If (-7) started from (-2)'s
house, how many steps did he take in order to catch the dog at (+1)? _____ Write an equation to
show how many steps he traveled.______________ Color the trail from (-2) to the dog on (+1)
brown, and draw a symbol at +1–oops that can of cinnamon was opened!

The last -2 saw of (-7) was when he was running down the street with the dog under his arm.
Oddly enough, when the experts were investigating, the cinnamon trail led to (+7)'s back yard!

When asked, Negative Six confirmed that (+7) has been (-7)'s mortal enemy since birth! When
asked where (+7) was on the night of the unfortunate event, (+7) simply stated that he was
watching a mystery movie. There were no alibis.

Weirdly enough, there were dog prints that went from (+2)'s house to (+7)'s house! Draw small
black dog tracks from (+2) to (+7) and write an equation to represent the path of the dog. Also,
Positive Six was sure that she heard dog barking noise coming from (+7)'s house even though she
swears Positive Seven does not own a dog!

There are many clues, but the trail is getting cold. What happened to (-7) after he picked up the
dog? Hmmm........

Do some investigating on your own and finish the trail of (-7) based on your own theory. Continue
from +1. You need to include at least 3 more stops and three equations. In the end, (-7)'s
unfortunate remains were found at the family reunion site at (-5)'s house. Finish your report by
stating who you think murdered (-7) and why? Be creative and use equations to support your
findings.

Your number line needs to be neat and easy to understand. Also, you need to write a paragraph
explaining what you believe happened to (-7) after he caught the dog. Don’t forget your
equations!
Role 3-Funeral Director: Your goal as funeral director is to write an obituary as a tribute to the great life
that (-7) led. Include in the obituary the time, date, and location of the funeral, (-7)’s accomplishments,
details about his career, and mention his family and friends who are grieving his loss. Refer to at least 10
grieving family members and/or friends. Many would be very offended if they were not mentioned! This
obituary needs to be typed. (You may use real newspaper obituaries as an example).
[An example of a family related to (-7) are the Centimeters. In the Centimeter family, there is (-5) the
father, (-4) the mother, and (+2) the baby. We know that this family is related because when you add them
together, they add up to (-7).]
Role 4-Grave Digger: Your goal as a grave digger is to design a cemetery on the coordinate grid that will
include the final resting place for (-7). His family wants to see all of the plots (at least 10) in the cemetery
where the x and y coordinates can be added or subtracted to equal (-7). Remember, they will be walking,
so each step counts as 1 unit.
Make sure your map is easy to read, and includes all points and coordinated.
Is it possible to represents grave plots in all four quadrants? _____ Why or why not? _________________
_____________________________________________________________________________________
Grading: See Attached Rubric