Ratios are everywhere! The scale on a map or blueprint is a ratio. Ingredients sometimes need to be mixed using ratios such as the ratio of water to cement mix when making cement. Watch this tutorial to learn about ratios. Then think of some ratios you've encountered before!
Use informal arguments to establish facts about the angle sum and exterior angle of triangles, about the angles created when parallel lines are cut by a transversal, and the angle-angle criterion for similarity of triangles.
You can't learn everything about math without dealing with triangles. Did you know that there are different types of triangles? Check out this tutorial, and learn about triangles and their different types!
Understand that a two-dimensional figure is similar to another if the second can be obtained from the first by a sequence of rotations, reflections, translations, and dilations; given two similar two-dimensional figures, describe a sequence that exhibits the similarity between them.
Looking at similar figures? Want to find a missing measurement on one of the figures? You could use a scale factor to solve! In this tutorial, learn how to create a ratio of corresponding sides with known length and use the ratio to find the scale factor. Then, write an equation using the scale factor to find your missing measurement!