String-Can Telephones: Lesson Plan

LESSON PLAN

STRING-CAN TELEPHONES

LEAD IN with SCIENCE OF SOUND

1. Have you noticed that when you talk and your voice fades, you take a breath? Why?

2. The sound of your voice starts with air passing over your vocal cord, AKA voice box. Your voice box will move (or vibrate) as you speak. Place your fingers over your vocal cords; your fingers might tickle as you speak. (Demonstrate; they try it.)
3. Think about what you do to direct your voice:
   To whisper, cup your hands around your mouth and speak softly into someone's ear.
   To shout, put your hands to each side of your mouth and shout to everyone.
4. Today we'll learn how to make our voice travel over a distance -– without shouting!

STRING-CAN TELEPHONES

1. This is what “telephone” means: (tele – = distant - phone = sound)
2. This is what happens when talking and listening face-to-face:
   As we've already seen, our vocal cords move -– they vibrate. And the sound wave travels in the air, which is called a medium. Your friend's eardrums vibrate – and he hears you!

3. This is what you can do when talking and listening over a distance: To do this without shouting -– make a string-can telephone!   (show one).
   a. Speak into the can. The string and can vibrate. The vibration travels in sound waves.
   b. The sound wave's vibration travels along the string to the 2^nd can, and then the other person hears. (Have 2 kids demonstrate.)                                                         c. c. You need to keep the string taut, as the sound travels best this way. Do not let the string sag or bend, either.

4. Show them how to make one. (Pass out supplies.)  Every 2 children make one set.
5. Try them out.
   WRAP-UP

1. Review what happens.
   air passes over vocal cord ----- vocal cord vibrates ----- sound wave travels through air to string at bottom of can ---- can and string vibrate ---- sound wave's vibration travels along the string to the 2^nd can ---- be sure to keep that string taut ---- the other person's eardrum vibrates and he hears you
2. Investigate further! use different kinds of cups and cans –--- use different kinds of strings ---- use different lengths of strings ---- chart the results * (see p. 2). What works best?
3. Pass out the leaflet; ask them to take it home.

Page 2

EVALUATION

Demonstrate it and explain to someone else how it works!

Notes on Vocabulary:

Underlined words: Put up signs you make or write them on the board.

Vocabulary: air – vocal cord / voice box – telephone – vibrate – medium – taut

Introduce whatever vocabulary seems appropriate for the group. Both “vocal cord / cords” and “voice box” are introduced and are used interchangeably. The medical term is:   l a r y n x.

Tips:

Cans are referred to in this lesson plan, but cups can be used instead.

The leaflet “String-Can Telephones and How They Work” can be used to show this visually.

Notes on the String-Can Telephones:

When you have some assistance in making the telephones, this lesson can be done in about 45 minutes. Making the holes in the cans/cups ahead of time will help to speed this up.

It's good if you have two sets of phones for two children to share (one for the ear, one for the mouth, so they don't need to keep switching one phone from ear to mouth). However, if time is limited, one set will do.

Plastic cups are easier to make holes in, so you might want to start with them. Later on, use different kinds of cans and cups and compare them.

You can introduce a variable in the type of string and/or can with the groups within the class. Each group would be assigned one kind of string / can:

Each group could use a fishing line / regular string / or dental floss

plus tin can / styrofoam cup / or plastic cup.

The different groups can swap and compare results using different kinds of string and cup. 

* COMPARING COMPONENTS USED IN STRING-CAN TELEPHONES

Cup or Can:	Different Types	of Strings:	RESULTS:
	GROUP 1 FISHING LINE	GROUP 2 YARN
Soup can, e.g.	X		Easy to hear
Styrofoam cup, e.g.		X	Hard to hear
Soup can, e.g.		X	??

Ask:  Why do you think you got the results that you did?

Kathy Dullea Hogan

Gateway to Science: Sports and Games

http://sportscience.blogspot.com

NOTE:  here is a good link to a page on WikiHow on string-can telephones:

http://www.wikihow.com/Make-a-Play-Telephone