iPhone, iSpy: Cell Phone Triangulation

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SWBAT understand how triangulation can be used to track cell phone location.

Big Idea

Cell phones have made communication exponentially easier, and they have done the same for crime investigation!


5 minutes
Please watch the video below before attempting this lesson!


I start each class period in this unit with a warm-up activity that targets forensic science concepts and other skills (observation, problem-solving, etc.) Not only does this get the students in the frame of mind necessary to address the field of forensics, but it also introduces key vocabulary they will use throughout the unit in a more relevant way. In addition, this activity allows students to refine their research skills as they perform quick internet searches to find the correct answers. By using the attached weekly Answer Sheet* and passing it out as they enter the classroom every Monday morning, not only can I save paper, but I can also provide a routine that allows students to begin without prompting, waiting for paper, or asking things such as, "What do we do?" and, "Where do we write our answers?"

For this particular lesson, I have decided to utilize a Video Challenge entitled, Forensic Entomology*, in which students watch a short video clip about forensics and follow up by answering an assortment of trivia questions.

After providing about 2-3 minutes to choose the correct answers, we go over them together and discuss the information provided. I help students to define key terms and providing background knowledge necessary to help students understand the questions. However, I do not spend as extended period of time on this portion, as it is just meant to be an activator and not necessary to understanding the core of the lesson at this time.

*Challenges and answer sheet courtesy of http://sciencespot.net/Pages/classforscistarters.html


10 minutes

I start this portion of the lesson by asking students to raise their hand if they have a cell phone. Most to all students at this age do carry a phone. If many do not, then I ask them to raise their hand if their parents own a cell phone. By this time, the whole class has their hand raised. I ask them to turn and talk about all the ways cell phones can be an important piece of evidence when investigating a crime.

After giving a few minutes to discuss, I call on random students to share one of the ideas that they talked about with their partner/s. Many come up with some creative (and perhaps nonsensical) ways that cell phones can be used in crime investigation.

Next, I have the students view the video, "Cell Phone Tracing leads to Crucial Evidence".

After watching, I challenge students to determine exactly how cell phones can be tracked, having them turn and talk again.


20 minutes

Next, I write the word "triangulation" on the board and tell students that investigators use triangulation to track cell phone locations. I ask the students if they can find any root words in the word on the board that will help them determine the meaning of the entire word. Students usually identify angle or triangle, and I challenge them to think about what angles or triangles might have to do with cellphone tracking. I ask them them to write down their ideas before we move on.

Next, I have students form pairs and pass out the two articles about cell phone triangulation - Cell Phone Triangulation and Cell Phone Tower Triangulation. I instruct the students to partner read the two articles, stopping to provide a brief oral summary after each partner take a turn reading.

After reading, I have them add to what they originally wrote, explaining the meaning of triangulation and how it can be used to track a cell phone, as well as how it might be used to help solve a crime.


30 minutes

Now that students have an understanding of what triangulation is and how it is used to determine location, it is time to practice a few examples. I pass out the Cell Phone Triangulation Activity*, provided by 21st Century Math Projects. Because of the advanced level of math *presented in this activity,  I allow students to choose between completing individually, with a partner or small group, or with my guidance. Students who choose to work without my guidance move to the back and/or sides of the classroom, while students who choose to work with me stay in the front so that I can model problems on the board.

After completing the activity, we discuss how triangulation works and why this would be valuable in the field of forensics.  Next, I pass out a few local newspapers from the past month and challenge students (in pairs) to find crime stories in which triangulation was used or may have been used to find a suspect or victim. As students find stories that relate to our learning topic, I have them share quotes or sections from the article that support their thinking.

*Please see my reflection for more information on this activity.


15 minutes

Students have now learned about what triangulation is and how it is used in an investigation. They have also practiced a few examples for themselves. As a final assessment, I want to see if they can apply their learning about triangulation and other forensic processes to the scenario of a crime scene. Students demonstrate their understanding by completing the attached exit ticket prior to leaving class.