Welcome to this deck on ratio and proportion. We'll start by understanding what a ratio is and how to write it in its simplest form. Then, we'll learn a key skill: how to share an amount in a given ratio. Finally, we'll explore direct and inverse proportion, which describe how different quantities relate to each other.

So, what is a ratio? A ratio is a way of comparing the size of two or more quantities. Think about making juice from concentrate. If you mix 1 part concentrate with 4 parts water, the ratio of concentrate to water is 1 to 4. It compares the parts to each other.

We write ratios using a colon. So, a ratio of 1 to 4 is written as 1, colon, 4. The order of the numbers in a ratio is very important. The ratio 1 to 4 is not the same as 4 to 1. In our juice example, 1 to 4 gives you a tasty drink, but 4 to 1 would be very strong!

Just like fractions, ratios can often be simplified. To simplify a ratio, you find the largest number that divides into all the parts of the ratio, and then you divide. This number is called the highest common factor.