Overview | The Trick | The Lesson

THE LESSON

Follow these steps:

1. Perform the magic trick several times.
2. Explain how to perform the trick.
3. Have volunteers perform the trick.
4. Lead a "build your own kit" session.

SHOWTIME (Steps 1, 2 and 3)

First, perform the magic trick for the class a couple of times. Then, explain how to do the trick, emphasizing that there is no magic involved — just a clever use of information. Finally, have volunteers perform the trick in front of the class.

This part of the lesson should be easy to implement and most kids will thoroughly enjoy it.

BEHIND THE SCENES (Step 4)

Reveal your secret

TEKS content: 2.4B, 2.5A, 2.5B, 3.2A, 3.2B, 4.4B, 5.3C, 5.5A.

Show the class your secret code machine. Explain that a number's code consists of a list of some (or all) of the numbers 16, 8, 4, 2, 1 — so the machine consists of cups labeled with these numbers. Now demonstrate how to use the machine to find a number's secret code. For example, here is how to find the secret code for 11:

• First, count out 11 beans.
  
  


• Divide the beans into groups of 2. You will have 1 bean left over — put it in the "1" cup.
  
  


• Rearrange the remaining beans into groups of 4. You will have 2 beans left over — put them in the "2" cup.
  
  


• Rearrange the remaining beans into groups of 8. This time there are no leftover beans, so the "4" cup will stay empty.
  
  


• Finish by putting your last 8 beans into the "8" cup.
  
  


• Read off the labels of the non-empty cups to find the secret code for 11 — and you'll get the sequence: 8, 2, 1.


• In order to recognize a number from its secret code, add the components of the code. For example, 11 = 8 + 2 + 1. (Of course — since the whole time you were playing around with 11 beans!)

Do a few more examples. Each time, arrange the beans first into groups of 2, then into groups of 4, then 8, and then 16 (until you run out of beans). Put the leftover beans at each step into the cup labeled with the corresponding number. You may want to have volunteers help you with the demonstration. (In this part of the lesson, children who do not grasp the relevance of the "why?" will be lost and bored. A good strategy is to choose these kids as helpers.)

Finally, perform the magic trick again — but this time do it openly, pointing out how each step of the trick reveals one more component of the secret code. (Tip: The number 22 provides a good illustration of the process.)

The Apprentice Magician

TEKS content: 2.6A, 2.6B, 2.6C, 3.7A, 3.7B, 3.15B, 3.15D, 3.16A, 3.16B, 3.17A, 3.17B, 4.7, 4.14B, 4.14C, 4.14D, 4.15A, 4.15B, 4.16A, 4.16B, 5.5B, 5.14B, 5.14C, 5.15A, 5.15B, 5.16A, 5.16B.

Surprise your friends and relatives! In this section of the lesson, each student will construct his or her own magic kit to take home.

Discover the Secret Codes

1. Give each student a secret code machine.
2. Divide the class into groups. Put each group to work finding the secret codes of the numbers you assign to them.
3. Display the secret code recording table on an overhead projector or the blackboard. As the groups compute the codes, fill in the information in the table.

Make the Magic Kit

1. Give each student 5 blank cards.
2. Have the students label the cards "1", "2", "4", "8" and "16" if they are using construction paper blank cards..
3. Using the information in the class recording table, have the children find all the numbers from 0 to 31 that have a "1" as part of their secret code. Have them write these numbers on the other side of card "1".
4. Repeat the process with the other cards.

Kits are ready!

Most students will like the hands-on work with the secret code machines. If time permits, have children play the trick with each other.

Comment

For an alternative way of finding secret codes, visit The Human Counting Machine.

Download the Lesson Kit (pdf)