© 21st Century Math Projects

© 21st Century Math Projects

CSI Whodunnit? Skill Builder – Systems of Equations

Standard Focus : Number, Number Sense, and Operations Time Range : 1 Period

Supplies : Pencil and Paper

Expressions and

Equations 8.EE

8b. Solve systems of two linear equations in two variables algebraically, and estimate

solutions by graphing the equations. Solve simple cases by inspection.

Reasoning with

Equations and

Inequalities

A-

REI

6. Solve systems of linear equations exactly and approximately (e.g., with graphs),

focusing on pairs of linear equations in two variables.

Procedures:

A.) Give students a CSI: Whodunnit Worksheet. Students will need to solve the 10 problems. Each correct answer will

result in a clue. Students will check off the Players, Last Known Whereabouts locations and Methods that are accounted

for. The one remaining from each column is the correct solution. In this case it should be “Miss Beta used electrocution

by the pool.”

This activity is modeled after my chain problems from my CSI Projects and the popular new Reality TV Show Whodunnit?

B.) Print out the Clues. Cut them out and. I suggest you laminate them for future use. Spread them in different locations

in the classroom and turn them loose. They will love it! Have teams of 2-3 circulate and attempt to figure out the clues.

Once they think they have all the pieces they can come to you to see. If they are wrong, let them figure it out

© 21st Century Math Projects

Name:_______________________________

Six contestants on a reality TV show were stunned to find their lowest scoring colleague was “murdered”. They

must figure out the crime before the bell rings. The question is Whodunnit? And how… The Player, Last Known

Whereabouts and Method that are left unaccounted for -- is the solution.

1. 2.

3. 4.

5. 6.

CSI: whodunnit?

© 21st Century Math Projects

7. 8.

9. 10.

Who is the Killer?

(The three boxes left unchecked will reveal the crime. If you cannot figure out, you may be next)

The Players The Last Known

Whereabouts The Method

Dr. Alpha Atrium Chemical Poisoning

Miss Beta Gym Drowning

Mrs. Gamma Kitchen Electrocution

Professor Delta Library Firearm Assault

Mr. Epsilon Movie Theater Mauled by a Cougar

Coach Omega Pool Venomous Bite

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𝑥 + 𝑦 = 9 𝑥 − 𝑦 = 3

(-6, -3) The murder was not done by chemical poisoning.

(6, -3) Miss Beta was reading in the library.

(-6, 3) The victim was not electrocuted.

(6, 3) Coach Omega was eating a snack in the kitchen.

CSI: whodunnit?

𝑥 = 2𝑦 − 20 𝑥 + 2𝑦 = 48

(14, 17) The murder was not done by chemical poisoning.

(0, 10) The victim was not mauled by a cougar.

(-24, -2) Professor Delta was reading in the library.

(-32, -6) Mrs. Gamma was lounging in the atrium.

CSI: whodunnit?

Clue #1

Clue #2

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𝑥 + 2𝑦 = 14 𝑥 − 3𝑦 = −11

(-5, 4.5) The victim did not have a venomous bite.

(0, 7) Coach Omega was lounging around the pool.

(4, 5) Mrs. Gamma was listening to music in the atrium.

No

solutions The murder was not an assault with a firearm.

CSI: whodunnit?

𝑦 = −2𝑥 + 8 4𝑥 − 2𝑦 = 8

Infinite

Solutions Mr. Epsilon was eating a snack in the kitchen.

(4, 0) The victim was not electrocuted.

(-3, 14) Miss Beta was watching a movie in the theater.

(3, 2) The victim was not mauled by a cougar.

CSI: whodunnit?

Clue #3

Clue #4

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6𝑎 − 5𝑏 = −8 2𝑎 + 5𝑏 = −16

(2, 4) Mr. Epsilon was reading by the pool.

(-3, -2) Dr. Alpha was watching a movie in the theater.

(-8, 0) The murder was not an assault with a firearm.

No

Solutions The victim was not mauled by a cougar.

CSI: whodunnit?

𝑥 = 5 − 2𝑦 3𝑥 + 2𝑦 = 17

(6, -1/2) The murder was not a drowning.

(1, 2) Mr. Epsilon was taking a nap in the atrium.

(-3, 11) The murder was not done by chemical poisoning.

Infinite

Solutions Dr. Alpha was swimming in the pool.

CSI: whodunnit?

Clue #5

Clue #6

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−4𝑥 + 5𝑦 = −10 20𝑥 − 25𝑦 = 50

(0, -2) The murder was not an assault with a firearm.

(10, 6) The victim did not have a venomous bite.

(-5, -6) Coach Omega was watching a film in the movie theater.

Infinite

Solutions Professor Delta was reading email in the library.

CSI: whodunnit?

6𝑥 − 6𝑦 = 24 𝑦 = 4𝑥 + 2

(4, 0) Mrs. Gamma was doing pilates in the gym.

(-2, 2) Miss Beta was reading in the atrium.

(-2, -6) The murder was not an assault with a firearm.

Infinite

Solutions The victim did not have a venomous bite.

CSI: whodunnit?

Clue #7

Clue #8

© 21st Century Math Projects

3𝑥 − 2𝑦 = −1 12𝑥 − 16𝑦 = 36

(1, -2) Coach Omega was exercising in the gym.

(-11/3, -5) The victim did not have a venomous bite.

(1/3, 1) Mr. Epsilon was reading by the pool.

(18, 20) The victim was not electrocuted.

CSI: whodunnit?

3𝑥 − 𝑦 = 18 −2𝑦 = −6𝑥 − 120

(-3, 7) The victim was not electrocuted.

(1/2, 4/5) The murder was not done by chemical poisoning.

(10, 12) Miss Beta was sunbathing at the pool.

No

Solution Mr. Epsilon was weightlifting in the gym.

CSI: whodunnit?

Clue #9

Clue #10

© 21st Century Math Projects

𝑥 + 𝑦 = 9 𝑥 − 𝑦 = 3

(-6, -3) The murder was not done by chemical poisoning.

(6, -3) Miss Beta was reading in the library.

(-6, 3) The victim was not electrocuted.

(6, 3) Coach Omega was eating a snack in the kitchen.

CSI: whodunnit?

𝑥 = 2𝑦 − 20 𝑥 + 2𝑦 = 48

(14, 17) The murder was not done by chemical poisoning.

(0, 10) The victim was not mauled by a cougar.

(-24, -2) Professor Delta was reading in the library.

(-32, -6) Mrs. Gamma was lounging in the atrium.

CSI: whodunnit?

Clue #1

Clue #2

© 21st Century Math Projects

𝑥 + 2𝑦 = 14 𝑥 − 3𝑦 = −11

(-5, 4.5) The victim did not have a venomous bite.

(0, 7) Coach Omega was lounging around the pool.

(4, 5) Mrs. Gamma was listening to music in the atrium.

No

solutions The murder was not an assault with a firearm.

CSI: whodunnit?

𝑦 = −2𝑥 + 8 4𝑥 − 2𝑦 = 8

Infinite

Solutions Mr. Epsilon was eating a snack in the kitchen.

(4, 0) The victim was not electrocuted.

(-3, 14) Miss Beta was watching a movie in the theater.

(3, 2) The victim was not mauled by a cougar.

CSI: whodunnit?

Clue #3

Clue #4

© 21st Century Math Projects

6𝑎 − 5𝑏 = −8 2𝑎 + 5𝑏 = −16

(2, 4) Mr. Epsilon was reading by the pool.

(-3, -2) Dr. Alpha was watching a movie in the theater.

(-8, 0) The murder was not an assault with a firearm.

No

Solutions The victim was not mauled by a cougar

CSI: whodunnit?

𝑥 = 5 − 2𝑦 3𝑥 + 2𝑦 = 17

(6, -1/2) The murder was not a drowning.

(1, 2) Mr. Epsilon was taking a nap in the atrium.

(-3, 11) The murder was not done by chemical poisoning.

Infinite

Solutions Dr. Alpha was swimming in the pool.

CSI: whodunnit?

Clue #5

Clue #6

© 21st Century Math Projects

−4𝑥 + 5𝑦 = −10 20𝑥 − 25𝑦 = 50

(0, -2) The murder was not an assault with a firearm.

(10, 6) The victim did not have a venomous bite.

(-5, -6) Coach Omega was watching a film in the movie theater.

Infinite

Solutions Professor Delta was reading email in the library

CSI: whodunnit?

6𝑥 − 6𝑦 = 24 𝑦 = 4𝑥 + 2

(4, 0) Mrs. Gamma was doing pilates in the gym.

(-2, 2) Miss Beta was reading in the atrium.

(-2, -6) The murder was not an assault with a firearm.

Infinite

Solutions The victim did not have a venomous bite.

CSI: whodunnit?

Clue #7

Clue #8

© 21st Century Math Projects

3𝑥 − 2𝑦 = −1 12𝑥 − 16𝑦 = 36

(1, -2) Coach Omega was exercising in the gym.

(-11/3, -5) The victim did not have a venomous bite.

(1/3, 1) Mr. Epsilon was reading by the pool.

(18, 20) The victim was not electrocuted.

CSI: whodunnit?

3𝑥 − 𝑦 = 18 −2𝑦 = −6𝑥 − 120

(-3, 7) The victim was not electrocuted.

(1/2, 4/5) The murder was not done by chemical poisoning.

(10, 12) Miss Beta was sunbathing at the pool.

No

Solution Mr. Epsilon was weightlifting in the gym.

CSI: whodunnit?

Clue #9

Clue #10