Students learn how to work out the gradient perpendicular, straight line graphs.

Later, as learning progress they are challenged to derive the equation of perpendicular graphs in the form y = mx + c.

**Differentiated Learning Objectives**

- All students should be able to calculate the gradient of perpendicular lines.
- Most students should be able to calculate the equation of a perpendicular line.
- Some students should be able to calculate the equation of lines in the form ax + by + c = 0.