Fractions
In the real world, there are not only whole numbers. E.g. bread can be cut into two halves and pizza into eight slices. To describe them we use fractions. They simply tell us how many parts of a whole we have.
Fractions show parts of whole numbers. Each fraction consists of a numerator and a denominator. The numerator is the top digit that represents how many equal parts the fraction contains. The denominator is the bottom digit that represents how many equal parts the whole is broken into:
There are many ways to write the same fraction. In the picture, you can see that $1/2$, $2/4$, $3/6$ and $4/8$ all represent the same amount. Even though the numerators and denominators of fractions are different, the colored parts of the boxes always show the same half of the whole.
We can also think of fractions as numbers on a number line. To represent $1/8$ on the number line, first draw a line from 0 to 1. Then divide the interval between 0 and 1 into eight equal parts (denominator=8). This gives fractions from $1/8$ to $8/8$ which is actually equal to 1 (and can also be written as $4/4$ or $2/2$).
