Return to WAFER ENCRYPTION (CANDY-GRAMS) Home Page.In addition, the students must devise a means to ensure that their messages will not get "garbled" during transmission. Student teams will split and go into different rooms when they are ready to test. Using only paper, the binding of a book, and/or the original plastic wraps from the candies, students need to design a system to keep their message parts together while you or another neutral party delivers messages between rooms.
There are several related engineering and mathematical concepts to this project. Specifically, encryption methods, encoding and decoding, digital processes, and number systems. Encrypting is the process of creating a system of secret writing based on a set of predetermined rules or symbols. Encoding and decoding are the processes of converting a message or information into and out of some code. The difference between encryption/decryption and encoding/decoding is that encryption processes are meant to be secret. One of the first uses of computers was in the 1940's by the British to break German secret codes.
Digital processes are those that use groups of electronic bits that are either on or off. Digital processes are based on a binary number system. Most students learn about different number systems in algebra (base two, base eight, base ten and base sixteen). This project gives them an opportunity to directly use other types of number systems (possibly base two, base three, base six, or some others) as a basis for their coding of letters and numbers, similar what digital computers use.
Each of these examples uses a different process for converting some information, whether pictures, sound, or letters and numbers, into an electronic form that can be easily manipulated. Without encoding and decoding processes our information society would be without information. This project gives your students a chance to develop a new, innovative way of communicating using an unusual material, SweetTarts.
An important aside to this project is cooperation and mutual support of all team members. Not only do all team members need to participate in the design of an encryption scheme, but each must also remember it and be relied upon to use it. Teamwork is not only important on the playing field; it is also important in the real world, particularly in design.
Testing is best done with two rooms, so you can divide each team in half and place them in different rooms. This eliminates any possibility of communication between team halves other than via the SweetTart message.
This project from introduction to testing requires at least four hours, which you can break into several blocks. There are several variations and extensions that you can add to this project, which will take additional time. Overall, it takes about two hours to design the process for encoding, decoding, and transmitting. You should allow the students about an hour to memorize and practice their process and an hour for testing.
Students will also need pencils or pens and paper, so they can write down portions of messages and such. Paper cups are also useful to hold spare SweetTarts. You will have to remind students to keep track of their SweetTarts. We suggest that after students encode the messages they place the spare SweetTarts in a cup so the other half of the team will have them available for the next message that they will have to code.
You will need a pencil or pen and a piece of paper in order to record the encoding and decoding times of the different teams. A digital stop watch will help you record the times; however, a wall clock will do if a digital stop watch is unavailable. You might be able to "borrow" a stop watch from another teacher or even from one of your students in the class.
You should encourage the students to test their process before they split up. They can easily test by writing on a piece of paper a sequence of SweetTart colors (i. e., Red - Red - Green - Orange, to signify four SweetTarts in that sequence), just as they would actually appear. Each student in a group can encode a short message to every other student in the team. Thus, with a team made up of four students, each student will encode three messages to send and decode three messages received.
After students have practiced their encryption process, they can split into two groups and test their process for arranging the actual SweetTarts such that they may be sent to another room. Students will overlook this aspect of the project if you do not remind them of it, and a good encryption process is doomed to fail if a message cannot be sent.
You can find the SweetTarts in most grocery stores. Each bag costs anywhere between $1.00 and $1.50. If you do not have paper cups readily available, then paper towels will also work.
It is best to make up appropriate length messages prior to class since you might not have enough time while students are designing. Your messages should be as close as possible to the message length limit of fifty characters (including spaces). Shorter messages will not fully exercise and challenge the student's processes. Adding numbers and words that use infrequent letters (i. e., q and z) will also challenge their schemes. The best messages to challenge the students will be those that do not have a large number of repeating letters and numbers and that cannot be deciphered from the context of the message. It is also a good idea to add some humor to the messages.
We recommend the following approach:
It is impossible to be in two rooms at the same time; however, if you should choose a central location (e. g., a desk or chair in the hall between two rooms) to use as a base. You will need to inform all teams that they must bring their messages to that location where you will record their times. If this is unworkable, a desk in the front of one of the rooms will also work well.
Encoding
To be fair, you will have to have each team encode the same message; therefore, you will need to distribute that message to all teams at the same time. The easiest way is to pass out folded pieces of paper with the message to each team. Start timing as soon as you begin to reveal the message. Since you cannot be in two rooms at the same time, you might want to start one room one minute behind the other. After you have distributed the messages, you can take your place at the base and record each team's time when they bring a message to you. You can label each message with a piece of tape with each team's name, so you can distribute the messages to the other half of the teams when it is time to decode. You will also need to ensure the secrecy of messages so that the other half of the class does not accidentally them.
Decoding
After all the teams have brought their encoded messages to you and you have recorded their encoding times, you can distribute the appropriate encoded message to each team for decoding. Again, each team should only start with a blank piece of paper and pencil. Fairly distributing the messages to each team and timing them is not easy. The best way to keep the students under control is to have them all get their messages from you and not start until all teams have their messages. Since the team halves will be in different rooms, you should again use the one or two minute delay between rooms.
For those teams that finish before others, they should bring their encoded/decoded messages to you at your base and then quietly return to their seats and wait until all teams are finished. If any teams disrupting, you can assess penalty time to those teams.
Variations
There are a number of fun variations to this project that you can undertake if you have time. They are only limited by your imagination and time available. One interesting one is to give each team a message that you have encoded using your own scheme. What they must do is decipher it and break your code. The team that does this with the fewest mistakes and in the least amount of time achieves the best score. For students to accomplish this task in a reasonable amount of time without a computer, you will need to give them a starting point or "hint". The best hint is to give them several letters and numbers from your process. They will then use their imagination and the message itself to fill in the rest of your scheme. This is a hard task!
Possible encryption methods can involve many different schemes. Students will surprise you with their ingenuity and creativeness. The most straightforward and easiest methods involve setting up a based number system and then assigning each letter, digit, and a space to a number. Using a based number system (such as a base three system with pairs of colors representing the digits 0, 1, and 2), each symbol will require a set number of SweetTarts. By representing a space with a SweetTart pattern, all symbols can run together. Thus, a message consists of a stack of SweetTarts that can be rolled in a piece of paper and transported.
MANY other encryption schemes are possible; however, all schemes must be able to represent the alphabet and in some way communicate numbers. When students design a method, you can ask them the following questions to make sure that they have considered all major aspects.
Your closure should remind the students that they have simulated a processes for sending and receiving detailed messages. This is the same type of process that satellites use to communicate with scientists and engineers back on earth. It also is the same type of process that computers and other digital devices like CD players, audio and video cassettes, etc. use to store information. The students acted like computer programmers by developing a process to encode and decode messages. They also simulated a computer by remembering their processes. In addition, the students designed a system to transmit their messages, just like a satellite dish and related equipment.
Finally, the students should realize that they have created a new way of communicating, although not directly practical. It may be far fetched, but who knows, someday we might run into a civilization that does communicate with a process using SweetTarts!
This project was developed by John Garcelon and Dr. David Jenkins.