Lesson Plan
Willow Tree

Angle Measurement

For Students 8th - 11th Standards
What do you create when you rotate a ray? An angle! Teach all the angle basics including naming, measuring, supplements, and complements. 
Handout
Auburn University

Auburn University: A Glossary of Political Economy Terms: Complementary Goods

For Students 9th - 10th
This site gives a good definition of "complementary goods" and provides examples. It also explains how when the price of Good A changes, the demand curve for Good B will shift.