Cliffs Notes Parent's Crash Course Elementary School Math
Chapter One
LESSON 1
Order and Magnitude
Most people think of numbers as a way of counting things, such as the number of students in a class
or the number of lemon seeds in a glass of iced tea. Counting certainly is one way to use numbers. The
numbers we count with are known as cardinal numbers. They have other names too, such as counting
numbers and natural numbers. Totally distinct from the cardinal numbers, but obviously related
to them, are the ordinal numbers. These are the numbers that are used to show position, that is 1st,
2nd, 3rd, ... 25th, and so on. Some elementary math teachers will dwell upon these distinctions, but
others will not. It is, however, a distinction that you should make sure that your child knows.
A much more important distinction exists in the meaning of numbers that some children are not
taught, but are left to stumble upon, if they ever do. Rather than spelling it out immediately, I'd like
you to consider the following diagram.
Suppose that we let the rectangle labeled "A" have a value of 1. Which rectangle would have a value
of 2? You didn't have to think about that for very long, did you? If "A" has the value of ... read full excerpt from CliffsNotes Parent's Crash Course Elementary School Math ebook
