Skill: Read coordinate graphs

To read a coordinate graph, first check:

1. The horizontal axis is the $x$-axis.
2. The vertical axis is the $y$-axis.
3. The point where the axes meet is the origin, $((0,0))$.
4. Read the coordinates in order:

$$(\text{horizontal position},\ \text{vertical position})$$

Example

A graph shows the number of books read during a week.

• The horizontal axis shows the day number from $0$ to $4$.
• The vertical axis shows the number of books, marked $(0, 5, 10, 15,)$ and $(20)$.
• Point $A$ is plotted at $((3,10))$.

What does point $A$ represent?

Step 1: Read the first coordinate.

The first coordinate is $3$. Move $3$ units along the horizontal axis. This tells us the day number is $3$.

Step 2: Read the second coordinate.

The second coordinate is $(10)$. Move up to $(10)$ on the vertical axis. This tells us the number of books is $(10)$.

Step 3: State what the point means.

Point $A$ means that on day $3$, the student had read $(10)$ books.

Remember: The first coordinate tells the horizontal position, and the second coordinate tells the vertical position. Do not switch $((3,10))$ to $((10,3))$.