Instructional Video
Khan Academy

Khan Academy: Proportionality Constant for Direct Variation

8th - 9th
This video shows how to solve an equation using direct variation.
Instructional Video
Khan Academy

Khan Academy: Algebra: Direct Variation 1

9th - 10th
This video demonstrates how to solve a word problem that involves a directly proportional relationship and rates. Given the price of gas per gallon and the total amount of money you must figure out how many gallons of gas could be...