Photo by James Cridland.
Aargh! My computer died again. So I borrowed my daughter’s laptop and ran off to the coffee shop to write blog articles — and discovered that all the outlets on the wall here are fake. Why would they do that? Anyway, before the laptop battery dies, I want to share a couple of math links with you…
Dave Marain of MathNotations is running a poll about how to teach multiplication, but the question has broader application:
How should we teach the arithmetic algorithms
— or should we teach them at all?
Algorithms are step-by-step methods for doing something. In arithmetic, we have standard algorithms for addition, subtraction, multiplication, and long division. Once the student masters the steps for any particular algorithm, he can follow the steps to a correct answer without ever thinking about what the numbers mean.
Math concepts: subtraction within 100, number patterns, mental math
Number of players: 2 or 3
Equipment: printed hundred chart (also called a hundred board), and highlighter or translucent disks to mark numbers — or use this online hundred chart
Place the hundred chart and highlighter where all players can reach them.
Are you ready for a challenge? Join us for the 2008 Mathematics Game. Here are the rules:
Use the digits in the year 2008 and the operations +, -, x, ÷, sqrt (square root), ^ (raise to a power), and ! (factorial) — along with parentheses, brackets, or other grouping symbols — to write expressions for the counting numbers 1 through 100.
- All four digits must be used in each expression.
- Only the digits 2, 0, 0, 8 may be used.
- Multi-digit numbers such as 20, 208, or .02 MAY be used this year.
- The square function may NOT be used.
- The integer function may NOT be used.
By definition:
[See Dr. Math’s Why does 0 factorial equal 1?]
For this game we will accept the value:
[See the Dr. Math FAQ 0 to the 0 power.]
As we all head back to school, here are some interesting calendar puzzles:
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.
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.”
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.
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
Place the hundred chart and a small pile of tokens where both players can reach them.
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:
Denise Gaskins' Let's Play Math 