(One or two class periods, depending on class level.) 4 Cost is lower if classroom supplies include rechargeable batteries for flashlights.

Students become familiar with the concept of a communication system, its various parts and functions. To do this, they encode, decode, transmit, receive and store messages for a hypothetical rescue mission, using a code sheet and flashlight for this process.They also maintain storage sheets from which they can retrieve information as it is required.

Coding and decoding make up a significant portion of electrical and computer engineering. Engineers design hardware and software for many devices such as radios, televisions, cell phones and computers that use one or both of these processes. communication system decoder destination encoder encryption receiver retrieval source storage transmitter Basic map reading skills, such as those used to play Battleship. Basic understanding of binary numbers. Understand digital data transfer. Understand the process of encoding and decoding. Understand the parts used in a communication system. flashlight (2 per group) simplified code table for each pair of students (see attachments) storage sheet (see attachments) pencil batteries for flashlight maps (see attachments) (optional) timer It is the middle of the winter. Four friends decide to go mountain climbing but none bothered to check the current weather report. Their families are worried because the climbers are already several hours late in coming home. All of the weather forecasters in the area are sure that the winter storm that is approaching will be really harsh and cold, and will leave a lot of precipitation. The entire city is shutting down and all the people are going to be in their houses; except you and the other members of your rescue team. You are a soldier working in a Special Forces Unit and you need to rescue those four misguided climbers before it gets dangerously cold and snowy on the mountain and they are stranded. Your unit takes you up the mountain in a helicopter but unfortunately, due to bad weather, you and your teammate are separated from the other pair who ended up at a different drop point. Your walkie-talkies and phones are lost in the process. Due to poor visibility, the roaring winds, and distance between the two rescue teams, the only way to communicate effectively is by using your flashlights. In addition, the current conditions are high risk for avalanches, which can be triggered by any type of noise, so talking is strictly prohibited. Once you have found the climbers, you must communicate whether or not they are wounded and their locations using flashlights, the map and the code sheet given to you. Once you have reached your climbers, tended to any of the wounded and prepared them for travel, you need to join the other pair of rescuers. After meeting, you are required to light a flare to show the pilot that you are alive and have completed the mission. Your goal is to complete this process in the least amount of time possible. A base-two number system that uses only 1s and 0s. It is the system used to store data in computer memories like RAM and ROM. A device that converts a message/signal into a code to prepare it for transmission. Therefore it is usually coupled with a transmitter. The process of converting a message into a code. A universal coding system used for computer communications. A device that converts the encoded data back to the original message. Any electronic device that stores data received making it accessible to the user. The third stage in data transmission (after encoding and storage) where stored information is accessed from the memory storage device. The position of the object or person receiving the signal or message. Make sure each group has a map for Team A and Team B. The map attachment provides sample maps as well as a blank map template for the teacher to edit. Do not hand these out before dividing the group of four into 2 teams. If using the blank map, mark the location of two climbers for Teams A and B on separate blank maps and make copies for the class. This way, you can change the location of climbers for each class that you repeat the activity with. Make copies of the code sheet (2 for each group; sample code for various characters and words). Make copies of the storage sheet (2 for each group; for recording data). Make copies of the procedure sheet (one of each kind per group). Divide the class into groups of four students each. In turn, each group needs to have teams of two. Read outloud the Introduction/Motivation section to the class (the "challenge"). Separate the teams in each group from each other and give them the maps, storage sheet, procedure sheet, table of codes and flashlights. Depending on the skill level of the class, allow time for practice. You may also want to do a sample demonstration for transmission of a short code. If you want to include a timing component to the activity assessment, start the timer when all groups have finished practicing and record how long each group takes to finish the activity. After students finish the activity, go over the Investigating Questions with them. Now technically define how a communication system works. Explain all the processes and tools used to communicate. Procedure for Teams A & B (doc) Procedure for Teams A & B (pdf) Maps for Teams A & B (doc) Maps for Teams A & B (pdf) Storage Sheet (xls) Table of Codes (doc) Table of Codes (pdf) Ensure appropriate use of flashlight and batteries Students may have difficulty with certain aspects of correctly transmitting or receiving the code. One solution is to give them enough time to practice and understand the process. It may help to them understand the process if you demonstrate a sample code transmission. Another possibility in lower grade classes is to hand out only the procedure sheet to the students beforehand (without the maps) and ask them to practice at home. Make sure both members of each team have practiced both the transmitting and receiving process. What or who represents the encoder? What does the flashlight do? After which process will the data received make sense to you? Why is storage important? When you are sending signals, who/what performs the role of the destination and who is the source? How important is error while transmission? Relate this to the universal system model. When given a map, students are able to successfully determine a location based on coordinates. Students should be able to successfully transmit and receive a code at the end of the practice session. Cross reference the data log sheets to see if the messages of Team A under transmitted data match up with Team B's sheet for received data and vice versa. Start a countdown clock when all teams are finished with practice sessions. Decide what an appropriate time limit is depending on the class level. Remind the class that unless they get to the climbers before this time, the climbers might be severely injured due to exposure to cold and may even die. These times may vary between 15 and 40 minutes. For more advanced classes assess where the team decided to meet, that is, whether they met closer to the team that had more injured or not. Correlate this activity to real life applications such as military communication systems. Explore different types of coding (Morse code, Braille etc) and how each has a different application. Research examples of codes are being used in the real world for communication through history. Assign investigative homework on how telephone, radio and TV transmissions are sent. Modify the number of climbers that have to be found. Reduce or increase time limits. Make the grid smaller. Ask students to come up with a code if they have already had some experience with binary numbers Give them more words to deal with and evaluate based on least number of words used. Give the map to only one team and ask them to direct the other team to locations avoiding the lake and rocks