Puzzles for the New Year

Posted on by Denise Gaskins
by Koshyk via flickr

As we all head back to school, here are some interesting calendar puzzles:

  • 2008 is a leap year. Why do leap years happen? If we didn’t add a leap day every so often, would January eventually come in the summer?
  • Today is Thursday. What day of the week will it be exactly one year from today?
  • January 1, 2008, came on a Tuesday. When will be the next year that begins on Tuesday?
  • My birthday (in March) lands on a Monday this year. When is the next year my birthday will come on a Monday? How about YOUR birthday — when is the next time it will happen on the same day of the week as this year?
  • Can you find a pattern in the way dates move from one day of the week to another, year after year?

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Christmas Puzzle Answers

Posted on by Denise Gaskins

Remember the Math Adventurer’s Rule: Figure it out for yourself! Whenever I give a problem in an Alexandria Jones story, I will try to post the answer soon afterward. But don’t peek! If I tell you the answer, you miss out on the fun of solving the puzzle. So if you haven’t worked these problems yet, go back to the original post. Figure them out for yourself — and then check the answers just to prove that you got them right.

Alexandria Jones and the Christmas Present Quandary

Magic Square Puzzles

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Magic Square Puzzles

Posted on by Denise Gaskins

Lo-shu turtle

Alex handed her brother Leonhard a box wrapped in the rocket tessellation paper, with air holes carefully punched in two sides.

“Merry Christmas, Leon!” she said.

He ripped open the gift. Alex winced. Boys have no artistic appreciation, she thought.

“Oh, cool! Thanks,” Leon said.

“His name is Lo-shu,” said Alex. “But be careful. I used non-toxic tempera paint. The design will was off.”

Leon turned the turtle and studied the back of its shell. “Oh, that’s just like in the legend! I’ll copy it down before I let him near any water.”

  • What do the shapes on Lo-shu’s back mean?
  • Why are some dots white and some black?

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Fraction Models, and a Card Game

Posted on by Denise Gaskins

Fraction cards

Models give us a way to form and manipulate a mental image of an abstract concept, such as a fraction. There are three basic ways we can imagine a fraction: as partially-filled area or volume, as linear measurement, or as some part of a given set. Teach all three to give your students a well-rounded understanding.

When teaching young students, we use physical models — actual food or cut-up pieces of construction paper. Older students and adults can firm up the foundation of their understanding by drawing many, many pictures. As we move into abstract, numbers-only work, these pictures remain in our minds, an always-ready tool to help us think our way through fraction problems.

Continue reading Fraction Models, and a Card Game

Game: Hundred Chart Nim

Posted on by Denise Gaskins

Photo by Håkan Dahlström via flickr.

Math concepts: addition and subtraction within 100, logical strategy
Number of players: 2 or 3
Equipment: printed hundred chart (also called a hundred board) and beans, pennies, or other tokens with which to mark numbers — or use this online hundred chart

Set Up

Place the hundred chart and a small pile of tokens where both players can reach them.

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How to Read a Fraction

Posted on by Denise Gaskins

Fraction notation and operations may be the most abstract math monsters our students meet until they get to algebra. Before we can explain those frustrating fractions, we teachers need to go back to the basics for ourselves. First, let’s get rid of two common misconceptions:

  • A fraction is not two numbers.
    Every fraction is a single number. A fraction can be added to other numbers (or subtracted, multiplied, etc.), and it has to obey the Distributive Law and all the other standard rules for numbers. It takes two digits (plus a bar) to write a fraction, just as it takes two digits to write the number 18 — but, like 18, the fraction is a single number that names a certain amount of whatever we are counting or measuring.
  • A fraction is not something to do.
    A fraction is a number, not a recipe for action. The fraction 3/4 does not mean, “Cut your pizza into 4 pieces, and then keep 3 of them.” The fraction 3/4 simply names a certain amount of stuff, more than a half but not as much as a whole thing. When our students are learning fractions, we do cut up models to help them understand, but the fractions themselves are simply numbers.

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More Fun with Hexa-Trex

Posted on by Denise Gaskins

Hexa-trex turtle logo

My elementary Math Club students had fun practicing their math facts and “out of the box” thinking with Hexa-Trex puzzles. The object of Hexa-Trex is to find a path through all the number and operation tiles to make a true equation. The “Easy” puzzles are just the right level for my 4th-5th grade students, although they get stumped whenever the equations require Order of Operations. One girl enjoyed the puzzles enough to take our extra pages home for her dad.

Hexa-Trex puzzles were featured in the October issue of Games magazine, and now you can enjoy Hexa-Trex away from the computer with Bogusia Gierus‘s new book, The First Book of Hexa-Trex Puzzles. If you are thinking ahead to Christmas (can it be that time already?!), and if you have a puzzle lover in the family, this little book would make a fun stocking-stuffer.

Quiz: Those Frustrating Fractions

Posted on by Denise Gaskins

[Photo by jimmiehomeschoolmom.]

Fractions confuse almost everybody. In fact, fractions probably cause more math phobia among children (and their parents) than any other topic before algebra. Middle school textbooks devote a tremendous number of pages to teaching fractions, and still many students find fractions impossible to understand. Standardized tests are stacked with fraction questions.

Fractions are a filter, separating the math haves from the luckless have nots. One major source of difficulty with fractions is that the rules do not seem to make sense. Can you explain these to your children?

Start with an easy one…

Question #1

If you need a common denominator to add or subtract fractions…

  • Why don’t you need a common denominator when you multiply?

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Ben Franklin Math: Elementary Problem Solving 3rd Grade

Posted on by Denise Gaskins

The ability to solve word problems ranks high on any math teacher’s list of goals. How can I teach my students to solve math problems? I must help them develop the ability to translate “real world” situations into mathematical language.

In two previous posts, I introduced the problem-solving tools algebra and bar diagrams. These tools help our students organize the information in a word problem and translate it into a mathematical calculation.

Working Math Problems with Poor Richard

This time I will demonstrate these problem-solving tools in action with a series of 3rd-grade problems based on the Singapore Primary Math series, level 3A. For your reading pleasure, I have translated the problems into the life of Ben Franklin, inspired by the biography Poor Richard by James Daugherty.

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Penguin Math: Elementary Problem Solving 2nd Grade

Posted on by Denise Gaskins

The ability to solve word problems ranks high on any math teacher’s list of goals. How can I teach my students to reason their way through math problems? I must help my students develop the ability to translate “real world” situations into mathematical language.

In a previous post, I analyzed two problem-solving tools we can teach our students: algebra and bar diagrams. These tools help our students organize the information in a word problem and translate it into a mathematical calculation.

Now I want to demonstrate these problem-solving tools in action with a series of 2nd grade problems, based on the Singapore Primary Math series, level 2A. For your reading pleasure, I have translated the problems into the universe of one of our family’s favorite read-aloud books, Mr. Popper’s Penguins.

UPDATE: Problems have been genericized to avoid copyright issues.

Continue reading Penguin Math: Elementary Problem Solving 2nd Grade