MEASUREMENT AND GEOMETRY
TWO DIMENSIONAL COORDINATE GRIDS
Did you know that numbers can have
relationships? Well they can. But what kind of relationship can they
have? How about the numbers 7
and 16 do they have a
relationship? 
So what is a
relationship between numbers? Its a rule which tells how to
make a new number starting with a different number. Suppose we have two
numbers, X and Y which could be any numbers at all. But we can make the
rule that Y always equals 3 times X. That rule is called a
relationship. Here is a table giving some values for the
realtionship:
A table is one way to show a relationship. Do you
know any other way? 
OK, but what is a
graph? A graph is a picture which
uses dots for values in a
relationship. Our graph will have two axes. The vertical axis will be for Y values and the horizontal axis
for X values. Let's have a look at a graph (also called a grid) with no
values on it, only the X and Y axis and the numeric
legend.
Next, let's put a value from the relationship, Y = 3X
of this grid. If we let X equal 1 what will Y equal? 
. Let's put that point on the
graph. That is called the point 1,3. We write the X value first,
then a comma, then the Y value.
