Numerous reports suggest an increase in white shark encounters* in the United States in recent years and the public is worried.
*Encounters include sightings and census estimates, as well as physical interactions between humans and sharks.
Carry out an investigation to model reliability of information flow for a device that encodes and transmits information within a system.
Some signals are reliable and some are not.
Click here for NGSS, CCSS (ELA), and California ELD standards.
In the previous lesson, students built an understanding that tracking devices that monitor white sharks use both acoustic (sound) waves and radio waves. They further explored that acoustic/sound waves attenuate in salt water and require a medium for transmission.
Students in this lesson embark on a journey of the development and application of wireless technology and compare wireless phones with tracking devices, considering reliability of signals and the encoding of information for transmission. Students practice with a binary code to understand how they can transmit a message and apply that understanding back to REMUS (and other tracking devices). They move on to understand that the tags that are on the white sharks, whose signals are picked up by receivers, begin as analog signals but are then encoded into digital signals before they are sent to researchers. Students are asked to consider which is the most reliable type of tag and which will have the most information by considering limitations of data. They will seek to improve precision and accuracy of data, and determine similarities and differences in findings. During this lesson, students apply understanding that systems may interact with other systems, may have sub-systems, and may be a part of larger complex systems. They will understand that models can be used to represent systems and their interactions such as inputs, processes, and outputs and information flows within systems.
In the next lesson, students will consider the challenge of actually tagging a white shark for study and how aerial surveys of white sharks misreport shark size thanks to the phenomenon of light distorting our perception of objects.
Throughout the lesson, a flag () denotes formative assessment opportunities where you may change instruction in response to students’ level of understanding and making sense of phenomena.
Part I | 20 minutes | Engage |
Part II | 25 minutes | Explore |
Part III | 45 minutes | Explain |
Question and define limitations and reliability of shark tracking systems encoding and transmitting information.
Student responses should include the following: more devices, more people using them, and more applications made available with new technology.
Ask students to consider what problems may arise as more devices are used by more people and scientists and as more devices use wireless technology. To give students a context for wireless communications leading up to the idea for smartphones, view the video, Ericsson: The History of Wireless Communication, from the archive of Ericsson at Centre for Business History, Stockholm, Sweden. Ask students to record any aha moments and questions as they watch the video.
Here are some ideas that students may come up with:
“The school has reliable WiFi because I am always able to connect to the Internet.”
Trustworthy and reliability are both terms that can take on many meanings depending on their context. In this case, a reliable signal is one that is consistent and that will not fail in the middle of a signal. A trustworthy (valid) signal is one in which all data transmitted is controlled in an orderly fashion, and is received in the correct order and is intact. At this point in the lesson, students may only be able to refer to the reliability aspects of a signal as that has been a part of their life experiences.
This exercise gives students the opportunity to participate in a discussion about reliability with a system that they already know, school WiFi, before they are asked to discuss a system with which they are less familiar, shark tracking systems, in Step 8.
From the video students should have realized that it is not always just one single device that is doing the tracking–there is always a transmitter and a receiver. For example, there can be a tag on a shark that REMUS is following and picking up data from, a tag on a shark’s dorsal fin and a satellite picking up and relaying data to a computer in the office of a scientist, or a tag on a shark and a hydrophone receiver picking up and relaying data to a computer in the office of a scientist.
Students analyze and interpret data to predict the validity of encoding and decoding signals between a shark tracking device and receiver.
In order to understand trustworthiness (or validity), students need to first understand how the information gets encoded before it is transmitted. As we speak into our phones or as the tracker picks up information from a shark, how does that information change in this process? The process of changing information from an analog signal to a digital signal is called encoding.
Be sure to gauge whether or not students are understanding limitations of data analysis and how better methods lead to precision and accuracy of data before moving on.
Students analyze and interpret data to determine how the scale of a system encodes and transmits information.
*Closed and open boxes refer to what students used in 8.7.H1: Binary Code.
The students should be guiding the conversation about how to represent the digital signal in a wave form. It is not too big of a leap for them to determine that sending one wave could be used to represent the 1.
As students model the input, processing, and output of different wave types for this type of messaging system, they should refer back to 8.1.H4: Crosscutting Concepts for Middle School Students (from Lesson 8.1: Shark Encounters) for the different parts of systems and subsystems. Give each person a role:
Number | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Received Number |
During this part, the actual amplitude of the wave does not matter so long as the Processor knows that a wave has passed. This is one of the reasons that a digital signal is more reliable than an analog signal. (It is discrete data.)
Amplitude | ||||||||||
---|---|---|---|---|---|---|---|---|---|---|
Received Amplitude |
During this part, the amplitude of the wave DOES matter. It will be much more difficult for students to actually get all of the amplitudes correct. This lack of certainty represents the “noise” or static in the signal. The amplitude of the waves represents a more continuous set of data that can be sent.
If students are talking about it, ask them to revisit 8.1.H3: My Shark Encounter Claim Chart from lessons 8.1–8.6 and add any new information that could be used to support any of the claims and subsequent evidence and reasoning. The writers, however, thought it would be a stretch to modify based on this lesson. Students will be prompted to revisit it again after Lesson 8.8: Light, Which Way Does It Go?
There will be variation in the prior knowledge students have around wireless technology, due to the digital divide. Pull up images from the Internet of wireless devices mentioned (or use realia) for the brainstorm in the Engage such as cell phones, radios, WiFi Internet, walkie talkies, drones, remote controls, garage door openers, remote controlled cars, laser tag, pet tracker chips, satellites, earbuds, or speakers. This will also be helpful for English Learners.
Allow multiple viewings of the video. The first time, have students to view it to get a sense of the purpose. Then, show the video a second (or even third time) to help students focus on important details that can be recorded in their Science Notebook and discussed.
Ensure students are clear on the meaning of key vocabulary such as encode, decode, binary code, digital and analog. Use word parts to reinforce meaning: encode–prefix en means in or within; decode–prefix de means separation; binary–prefix bi means two. To create a concrete depiction of analog vs digital, show a visual image of a clock with moving hands for analog contrasted with a digital clock set to the same hour (just numerals).
Lastly, students having difficulty with the model for input, processing, and output of different wave types, should be invited to repeat the task. This can assist them in coming up with a set of procedures.
CSULB Shark Lab (2017, July 18). NGSS Learning Sequence: Jawsome. Retrieved from https://youtu.be/CajgBDBOkLk
Ericsson (2011, August 26), The History of Wireless Communication. Retrieved from https://www.youtube.com/watch?v=X5jPoQzEh-M
Tretter, Thomas. “Teaching Electromagnetic Waves Used in Communication Technologies.” Science Scope, Oct. 2014, pp. 78–86.