I have used this activity many times with high school students. It is done as a race, with as many teams as you wish. It based on the old game of Telephone, where a phrase is whispered from one person to another, generally with the ending having little similarity with the beginning.
You can have a number of stated objectives with this activity: to investigate various forms of communication, to transmit a coded message, to listen and forward a message accurately, etc. It can also be used as a form of subject review by substituting words or definitions for the messages described later. Or it can just be for fun.
It is a great activity for Boy Scouts and can incorporate several different forms of communications.
Step 1: You Will Need...
You'll need as many pairs of communications devices as you can find - or at least, as many as you want to use.
In my classroom, I have used pairs of tin can telephones, walkie-talkies, signal flags, and Army field telephones. As each pair of devices requires a pair of operators, three of them require six people on a team. Most of the time, you will have an odd number of people, so you can use them as runners, taking the original message to the first team member, and receiving it from the last.
There is a good chance you won't have a set of field phones. In this case, you can add more tin can phones, and if necessary more walkie-talkies. Unfortunately, the more radios you have, the more goofing around the students will do; that seems to be a natural result. Additionally, a pair of radios for each of two teams requires two different channels; two pairs require four channels, etc., which requires some thought. The simplest way of keeping students from being on the wrong frequency is to write the frequency and tone on a piece of tape and stick it to the back of each radio as you set them up. That's still not going to guarantee they won't deliberately be off the channel.
Everybody knows how to use tin can phones, but you need to remind them anyway - keep the string tight. They just don't work with a droopy string.
Step 2: What Makes This Different
So far, this activity isn't a lot different from others you may have done. What make this one different is the messages transmitted.
You may have begun the unit by explaining that communication is the exchange of intelligence, however what will be transmitted in this exercise is woefully unintelligent.That's what makes it fun. In this case, it isn't so much that you're communicating something that makes sense, as you are communicating something.
You might point out that, during World War II, the radio signal to the French Resistance that the Normandy Invasion would happen within 48 hours wasn't a code word, it was a phrase from a popular song. It wasn't what the words meant, it was that they were said at all.
Once you determine how many students (or scouts, or whatevers) you have on each team, and decide what kind of devices you will use, you will next want to come up with a practice text. Instead of The Quick Brown Fox or the like, I use lyrics from nonsensical songs.(or at least songs that seem nonsensical.) Some of them I have used are:
I Am The Walrus - the Beatles
Mean Mister Mustard - the Beatles
Come Together - the Beatles
Mairzy Doats - various artists
I'm Being Followed By a Moon Shadow - Cat Stevens
Blinded By The Light - Manfred Mann
Porcupine Pie - Neil Diamond
and a bunch more.
To begin with, once you have your operators in place, run a quick check to make sure everything is working. This amounts to merely having each kid wave when they receive a code word from the operator in front of them in the chain.
Once you have run a 'commo check' of your equipment, select a phrase that seems appropriately goofy and provide it to either the runners or the first communicators on each team. You might want to have several typed up on slips of paper.
Remember, most young people will not be familiar with these songs. It's hilariously funny to hear the kids repeating things like "Goo Goo G'Joob" with increasing frustration as they try to get their message through.
The winning team is the one that forwards to you the most accurately transcribed message in the shortest time.
Step 3: Alternatively
You might want to do this activity outdoors. You have a choice, use the same equipment to send the same type of message, or use some combination of equipment, along with Morse Code by means of flags, lights, and/or horns. In this case, the text should be about ten jumbled letters, and each team should have a code key. Because each letter will have to be looked up, it takes much longer to transmit even a short message.
Note: Using Morse this way is fine for proving that it can be used to send a message. However, it is not the way to actually teach Morse for either visual or audible use. Introducing a code table adds a step to the process that is unwanted in actual usage. A skilled operator hears a character, or sees it by means of a flashing light, and immediately recognizes the character without thinking of the letter on a table.