Math Magic Tricks & Expressions

The concept of teaching students how to write algebraic expressions throws me every year.
Why?
Probably because real life doesn't throw out cookie cutter situations that are easy to figure out when to add, multiply, subtract or divide.
I don't want to just teach them how to write expressions such as:
twice a number,
3 more than 1/2 a number,
or 7 less than 4 times a number.

Vocabulary is important.
But even if vocabulary has been mastered, it can still be a very confusing concept.

So how do I engage students in the process?
How do I grab their attention so they can see WHY they are writing expressions?
How do I make it meaningful in their world?

This year, I'm going to use those "Think of a Number" puzzles.
They are always intriguing as to how the teacher knows the number you only thought of in your head.
Every kid loves magic.
This is a form of math magic.
With which I'm going to hook 'em into learning algebraic expressions.

After all, isn't the number that holding hostage secretly in their mind
the same as a variable?

Using this method, we'll be able to reinforce other skills.
The Order of Operations.
Distributive Property
Simplifying
Like terms

This website offers problems that aren't too complicated.
A great place to start.
Plus, it's interactive so students can click through them at their own pace.
PLUS, it offers puzzles from both viewpoints:  where the student thinks of a number and the computer guesses, or the computer thinks of one and the student must figure it out.
http://www.hellam.net/maths2000/thinkno1.html

More problems:
http://www.ehow.com/how_2257812_do-number-magic.html

This website is much higher level, but I'm going to have it available as I can see some classes/students needing this challenge.
http://www.ehow.com/how_4742479_telephone-number-math-magic-trick.html

The website is just for fun...to see if students can see the math behind it.
http://www.learnenglish.org.uk/games/magic-gopher-central.swf

This website is also a great interactive website to wow and amaze students.  The trick can be put into an expression.  Great review of place value.
http://www.digicc.com/fido/

So, all of these great ideas, don't get me my original goal.
To be able to write expressions of everyday situations.
But it is a great way to introduce how everyday vocabulary actually means add, subtract, multiply, and divide.
My hope is that once students can master the Math Magic Tricks the "real" stuff won't seem so daunting.  :)

Another idea:  Algebraic Expressions Millionaire