Calculus relates measurement and time. Calculus models how things change one with the other. Differentiation yields the slope (or rate of change) on a graph at any point (or instance in time). Integration yields how much of something has occurred within time boundaries (or the area under a curve). Calculus is an abstraction of mathematics however its comprehension is within the grasp of many.
Prior Knowledge & Skills
Follows on from equations and algebra. We need to understand rate of change and knowing how to read a line graph is very important.
Finding the slope on a curve often forms the start of differentiation. Application in the real world follows. Finding the area under a curve forms the basis of integration. The area between two curves can follow this. Examination of applications in engineering considering dynamics and electronics is more advanced.
Modelling and making sense of trends and projections is a skill, whether that be in finance for portfolio investment, or in engineering to work out limits in design.
Get an idea of calculus from this PowerPoint: