This video introduces ratios so that you'll have the basics of what ratios are, how they are written, and what they mean. These are key basics whether you're studying similar triangles in geometry or you're about to take the SAT.
Properties Of Ratios
This is sort of an algebra topic, but usually where you'll need to know it is in Geometry. This video starts with basic geometry problems about similar polygons and triangles, but then it gets into honors topics such as how to compare ratios and ratio "properties".
The Golden Ratio
The Golden Ratio is a very specific ratio -- 1 to 1.618 -- that can refer to either a segment or a rectangle. This video explains what the ratio is and where it comes from, and it also shows you how to use it in word problems.
If you do not have an account, you should get one, because it is awesome! You can save a playlist for each test or each chapter, and save your "greatest hits" into a "watch right before the final" list (not that we recommend cramming, but when in Rome...)