Here is a line:

The arrows at each end show that the line really goes on forever.

Each place on the line is called a point. A few of the points on this line are marked with red dots:

We can number some of the points to make them easier to find. The numbers get bigger from left to right:

Right now, Sam is sitting on point 4:

On this line, only the even numbers are labeled. The other numbers are marked like this: I. This mark is called a tick mark.

If Sam wants to find point 5, what should he do?

Sam starts at 0,

and crawls forward. Sam knows that 5 is 1 more than 4, so he counts one tick mark after 4.

Now Sam is at point 5.

Sam makes a big green dot to show where he has been. He labels the dot too, so you can tell what it is.

Sam just graphed point 5.