Geometry starts from introducing undefined terms, like point, line and plane, and then building on those. In this video I introduce these undefined terms and basic definitions, as well as notations.

Postulates are like undefined terms. They are logical statements that just make sense. We don't need to prove them, they are obvious. But they are another building block in geometry.

One of the first proofs in geometry is a perpendicular bisector proof. We constructed it by connecting points of intersection of two circles. But why is this line a perpendicular bisector?

Once we know the definition of a ray, we are ready to define an angle and look into different types of angles.

Before moving on to geometric proofs, we can circle back to algebra and see how every step in solving an equation was supported by a certain property.

This is a recording of my lesson on dilations, after we learned other geometric transformations.