Scales of measurement are often direct scales. This means that the value representing the quantity of an item is bigger, the more there is of that item.
The following is a simple example of direct measurement: Imagine you had 20 tablets. If you put five in each bottes you would have 20 ÷ 5 = 4 bottles.
However, if you had 40 tablets and again bottled them in fives you would fill 40 ÷ 5 = 8 bottles.
So, as the amount of tablets increases, the number of bottles needed to store them also increases. If you know the number of bottles then you could work out how many tablets you had, and vice versa. This is direct measurement.