I'm betting that many readers of the "Magical Equations" section are math teachers. I'd love to know how some of you teachers sprinkle magic into your lessons. What effects do you do?

I've taught college mathematics for nearly 20 years.

I rarely do any magic during class, except for the last class before finals week. That class comprises:

• Handing back the last mid-term exam and going over the answers
• Reviewing for the final exam
• Magic show

I figure that if they've put up with me for the entire term, they deserve a reward, which is usually a 30 - 45 minute close-up / parlor show.

Thanks for that nice idea. I'd like to be a student in that class!

I'd also be interested in hearing how some magic effects relate to specific mathematical topics. As an example, in a lesson on probability, one could ask the class to find the probability of predicting the result of a sequence of coin flips. After doing the work, the teacher could *amaze* the class by making an accurate prediction (using any number of methods).

Any thoughts?

I'm not a math teacher, but my high school algebra teacher had a "Fun with Math" day at the end of the year and I did the old math prediction trick of writing the numerals
9 8 7 6 5 4 3 2 1
on the board. I had one of my classmates circle any three consecutive numerals--like 543--and write it on the board. Then we reversed the digits and wrote the new number (345) under the first and subtracted the smaller from the larger
543
-345
with the answer 198. I showed my prediction and wowed the class.

Years later when I became a school librarian, I began to use the 198 trick to force a page number in a dictionary. A student looked at the guide words on page 198 of the dictionary, and I promptly began to get impressions that the guide words had x number of consonants and vowels... x number of syllables.. and finally revealed the guide word. (Of course, I had peaked at the guide words in advance.) This was a great trick featuring not only featuring math skills but dictionary skills as well.

----- Amado "Sonny" Narvaez

I'm not a math teacher but I love math.

"Predict a Number on Any Cell Phone!"
http://www.youtube.com/watch?v=rbBymb4NU3
I did this trick in my number theory class. Students are convinced that modular arithmatic is useful.

I also demostrate Penney's game, when teaching basic combinatorics and probability.

Hi all,

I like to do the following in my Elementary Statistics classes when reviewing the probability axioms. I bring out a deck, false shuffle, and then:

1. First student selects a card and I ask, what is the probability he selected a card (!). This illustrates P(sample space)=1.

2. Second student selects a card and I ask, what is the probability she selected the Fifteen of Diamonds. This illustrates P(empty set)=0.

I then continue talking, and eventually the second student notices that she has in fact selected the Fifteen of Diamonds!

Obviously, I have forced the gag card. I always do this as a throwaway, not a magical effect, and just continue reviewing the other probability axioms as though I hadn't noticed anything unusual. The student's expression when realizing she has the Fifteen of Diamonds (after the entire class had just said the probability is zero) is hilarious, and ripples through the entire class.

Thomas Henry