# Category Archives: Mathematics

## Math Game: Hangmath

What is it?
Hangmath is paper and pencil game similar to Hangman.  Players take turns creating two-digit addition problems, which the other player guesses.

Rationale:
Hangmath reinforces place value concepts because the Magical Minds must ask questions about the digits in different places.  Hangmath also provides practice in adding two-digit numbers.

How to Play:
1) Create a two-digit addition problem.  Use a dice to determine the digits.  Add the two two-digit numbers together to find the answer (the answer may be a three-digit number).  Write these numbers SECRETLY on the “Hangman’s Sheet.”

For example:
I roll a 4 and a 6  = 46
I roll a 5 and a 2  = 52

52
+ 46
________
98

2) The Guesser uses the guide sheet to ask questions about which digits are in the different columns.
For example: “Is there a 3 in the ones column?”

3) If the guesser guesses wrong, the Hangman draws one body part on the Hangman’s sheet.

4)  If the guesser guesses correctly, they begin to fill in their answer on the top of their sheet.

____   2
+   ____  ___
_____________
___  ____  ___

5) If the Guesser figures out the problem (he/she must know ALL the numbers in the problem, not just the answer) before the Hangman is complete, he/she wins.

## Math Game: Foreheaded (place value)

What is it?
In this game each player receives a mystery three-digit number, which they place on their forehead.  Using a guide sheet (below), players take turns guessing the digits in their numbers.

Rationale:
This game allows the Magical Minds to practice the language of place value.  Players will use the vocabulary of ones place, tens place and hundreds place to determine their digits.  This game also supports the understanding of strategy.  Broad questions such as “is it larger than five?” or “is it even?” allow for players to more quickly narrow down their number.

How to Play:

• Each player secretly writes down a three-digit number and gives it to another player.
• Players take turns asking questions (using the guide sheet) to determine their number.
NOTE: Each question must be written down on the guide sheet.
• When a player thinks they know their number, they use their turn to announce their number.
• First player to determine their number wins.

## Roman Numerals, Invisible Ink and Chemical Reactions

The best part about Roman Numerals? Its like a code.  Codes are cool. You know what else is cool?  Invisible ink.  Even better…chemical reactions.

It all began with a math puzzle.  During snack, each Magical Mind was give a number, written out.  For example, nine hundred and nine.  Their task was to figure out how to write the number with digits. For example, 909.

There were four numbers, and after snack I asked the kids with the same numbers to form teams.  They worked together to write their numbers, and then I gave them a challenge.  “Work with your team to write the Roman Numeral for your number.”

Now for the invisible ink.  I wet a paintbrush in some brown liquid and painted a white piece of paper.  The liquid turned the paper a shade of bluish-purple, except where I had secretly written a Roman Numeral.

Each team received a small vial of “mystery liquid” to write/paint their Roman Numerals.  They worked with each other to share materials and write their numbers.

After setting our hidden messages aside to dry, we took a short break to clear our minds. I needed them to shift their minds from thinking mathematically to thinking scientifically.

The invisible ink works because of a chemical reaction.  In order to help the Magical Minds understand what a chemical reaction is, I invited them to participate in a science experiment with Alka-Seltzer and baking soda.

Each team got a set of four test tubes filled with clear liquid.  I informed them there were only two different kinds of liquids and asked them to use their senses to determine what the liquids were.

With some investigation the Magical Minds quickly discovered the test tubes held either water (“pool water” was the most common response) or vinegar.

Each team was given a small piece of Alka-Seltzer and instructed to place half of the tablet in each liquid and observe the reaction, if there is one. I let them know that if they see a change in the liquid or a change in the Alka-Seltzer they would know it was a chemical reaction.  After watching the bubbling and fizzing, the kids agreed that the Alka-Seltzer reacted with both liquids, but it had a stronger reaction in the water.

Next, each team was given a small vial with baking soda.  I asked them to test 1/8 tsp in each remaining test tubes and look for chemical reactions.  As you may have predicted the Magical Minds detected no chemical reaction when they added baking soda to water, but were giggly and excited when they witnessed the foaming reaction between baking soda and vinegar.

Armed with a burgeoning understanding of chemical reactions, the Magical Minds returned to the invisible ink.  I demonstrated how I added iodine to water to create the brown-ish liquid.  “Paint the iodine water on top of the invisible ink and look for a chemical reaction.”

What do you think?  Does the iodine react with the lemon juice?

## Roman Numerals and Place Value

We have been studying how to read and write Roman Numerals.  Unlike our number system, Roman Numerals are an additive number system.  It doesn’t matter where the digits are, but rather it matters how they add up.  In our Hindu-Arabic system we have 10 digits (0-9), which change in value depending on where they are placed.  My goal is to illuminate the importance of place value by juxtaposing these two different systems.

But, for now we are just playing with Roman Numerals.  It’s fun.  It’s like code.  This week I introduced a game of Roman Numeral Memory.  Since the numbers can be quite challenging to decipher, we have kept them face-up and simply matched pairs.  Want to make a game yourself?

## Math Games: Two-Card Match-Up

Why are we playing Match-Up?
In this card game, the Magical Minds practice using their knowledge of place value to create large numbers.

The Goal is to win ALL the cards by having the highest number.

How to play: (very similar to War)
1. Remove the 10’s and face cards
2. Split the deck between two players
3. Each player turns over two cards.  Each player then rearranges the cards to create the largest number possible.  For example if I draw a 5 and a 9, I can create the number 59 or 95.  I would want to create the number 95.
4.  The player with the highest number wins that round and takes all the cards.

IF YOU TIE:
Each player draws two more cards and the highest number wins.

## Math Games: Pyramid 13

Why are we learning Pyramid 13?
We continue to solidify our understandings of the basics of playing cards. During our math lesson we discovered the names of the four suits, and how many cards are in each suit.  Through this game, the Magical Minds also practice some basic math facts.  To win the game you must make pairs that equal 13 (for example a six and a seven).  This constant hunt for 13 pairs helps increase automaticity as well as improves basic addition facts.How to Play:
Pyramid 13 starts with 28 cards arranged in a pyramid on the table.  Start with a row of 7 cards (facing up).  Above those cards create a row of 6 cards (facing down).  Above those cards create a row of 5 cards.  Continue until your pyramid looks like this:

The goal of the game is to get rid of all the cards in the pyramid.  You can remove cards when you create a pair that equals 13.  Kings are a freebie and can be automatically removed because they equal 13.  As you remove cards, the down-facing cards become “free” to turn over once they are no longer touching any cards in the row below.  If you cannot make 13 with the cards in the pyramid, turn over the extra cards one at a time to help you make pairs.

## Math Games: Gin Rummy

Today we learned how to play the most simple version of Gin, or Gin Rummy.  This is probably the most commonly played game in my household.  It is a game that I grew up with.  I invite you to take a deck of cards wherever you go.  Gin can easily be played at the park, on a plane, or at a coffee shop.
Why are we learning how to play Gin?  This year the Magical Minds will be playing with cards a lot to improve their math skills.  This introductory card game will allow the Magical Minds to learn how to shuffle, deal, take turns, hold cards and familiarize themselves with the numbers and suits.  Later on we will use card games to solidify math skills such as subtraction and multiplication.Instructions:
Every player gets 7 cards.  The remaining cards sit in the middle, and the dealer turns one over to start the “discard pile.”

You can either play with the cards in your hand, or with the cards spread out on the table in front of you.

The goal is to group all of your cards into either sets or runs.

A set = 3 or more cards of the same number
A run = 3 or more cards in consecutive order (eg. 4, 5, 6).  Note: They not have to be of the same suit (that is a more challenging way to play)

The person left of the dealer goes first.  When it is your turn, you must pick AND discard.  You may choose the top card from the discard pile, or choose a fresh card from the deck.  But, you must always choose one card to discard.

When you all of your cards are in either sets or runs, turn your discard upside down and holler “GIN.”  This is how you win.

Enjoy!