
Graph TMD1 
In Graph TMD1, the graph of the table values of the
function $f$, we identify each pair of numbers $a$ and $f(a)$ from
the table with the point in the plane with coordinates $(a,f(a))$.
In Diagram TMD1, the mapping diagram of the table
values of the function $f$, we identify a point on the source
line (on the left) with a number in the $x$ column on the table,
$a$. We identify a point on the target line (on the right) with
value of the function $f$ applied to that number, $f(a)$ also
found in the table next to the number $a$. An arrow is drawn from
the point on the source line, $a$, to the corresponding point on
the target line, $f(a)$, that visualizes the relation between the
corresponding numbers in the table.
For example, consider the pair from Table TMD1, $1$ and
$5$. In Graph TMD1 this pair corresponds to the
point in the graph with coordinates $(1,5)$. In mapping Diagram
TMD1 this pair corresponds to the point $1$ on the left
line of the diagram, the point $5$ on the right line the diagram
and the arrow from the points representing $1$ to $5$ indicating
the function relating the two numbers.
A mapping diagram visualizes a corresponding function table. The
numbers in one row of the table are represented by points on the
two lines in the figure. The function relation that the table
displays implicitly by having corresponding numbers in the same
row is visualized in the mapping diagram by the arrow. While
the relative size of the numbers in the target column of the table
is not represented in the display, the mapping diagram uses the
number line order to represent this aspect of the function's
values.