Ratios are so important as they are used regularly in every day life. Making mistakes with ratio can cause incorrect medication or wrong concentrations of dangerous chemicals. Ratios matter!
But ratios are difficult because they are poorly understood. Most students do not realize that a ratio is another form of a fraction. The ratio however does not look like any of the other written fractions; for instance 1:3 does not look like 1/4 rather it looks like 1/3. Where does the the 4 come from?