Math Is Not A Trick

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Math Is Not A Trick

• December 15, 20097th GradeDavid RockDean
  College of Education
• Columbus State University
• rock_david_at_colstate.edu

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Frog in the Pond
There is a circular pond with a diameter of 200
feet. Dead in the center of the pond is a frog
on a lily pad. The average leap of a frog is two
and a half feet, and there are plenty of other
appropriately spaced lily pads in the pond on
which to jump. What is the minimum number of
leaps it will take the frog to jump completely
out of the pond?
200 feet
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Thoughts to ponder?
Did you get 40 or 41?Where did you start?Is
the edge of the pond completely out?
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Patterns are puzzling fun for all!

• 1, 3, 5, 7, ___, ___, ___
• 1, 2, 4, 7, ___, ___, ___
• 1, 1, 2, 3, 5, ___, ___, ___
• A, C, E, G, ___, ___, ___
• O, T, T, F, F, ___, ___, ___
• J, F, M, A, M, ___, ___, ___
• By the way, what is the least (smallest) whole
  number that uses the letter A in its English
  Language spelling?

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Card Tricks are Fun
Pick a card and concentrate on that card!
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Its Magic!
I threw out your card!
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Card Tricks are Fun
Pick a card and concentrate on that card!
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Its Magic!
I threw out your card!
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Pick a number

• Pick a number and write it down
• Add 2
• Multiply by 4
• Add 12
• Divide by 4
• Subtract 5
• What did you get?

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This image is not animated.  Your eyes are making
it move.  To test this, stare at one spot for a
couple seconds and everything will stop moving. 
Or look at the black center of each circle and it
will stop moving. 
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Pick a number

• Pick a number and write it down
• Add 4
• Multiply by 2
• Add 14
• Divide by 2
• Subtract your original number
• What did you get?

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Mind Reader

• The Flash Mind Reader

http//www.cyberglass.biz/flshstuff/mindreader.php
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Cute Little Bookworm
There is a three-volume set of books sitting on a
shelf. The front and back covers of the books
are each one-eighth inch thick. The page section
inside each book spans exactly two inches. A
cute little bookworm starts eating at page one of
volume one and eats, in a straight line, through
to the last page of volume three. How far will
the little worm travel?
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Strategies

• The answer is not six and one-half inches.
• HINT Try the problem!
• Drawing a diagram is a great strategy but you
  are not physically trying the problem!

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Not Tic-Tac-Toe

• Toe-Tac-Tic The object of the game is to get
  three in a row! What skills are used to play
  this game?
• Not-Toe-Tac-Tic The object of the game is to NOT
  get three in a row! What skills are used to play
  this game?

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Handy Man

• A man walks into a hardware store and buys1
  for 120 for 2 300 for 3
• What is the man buying?

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Do you see gray areas in between the squares?
Now where did they come from?
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19 1 20
How can you take one away from nineteen and get
twenty?
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Roman Numerals?
XIX is 19Take away the I and you get XX which
is 20
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Are the purple lines straight or bent?
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Place 8 Xs on this grid such that no 2 Xs are in
the same row, column, or diagonal
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Problem of the Week Contest
www.colstate.edu/mathcontest
The Elementary Brain Teaser Middle School
Madness Algebra in Action The Problem of the
Week