I can measure the magnitude of the force from the fan by turning it on and letting it push up against a force probe. With this, it seems to push with a force of about 0.2 Newtons (your fan may vary).

But if you calculate the acceleration without the graph, you are explicitly stating that the y-intercept is zero---which it might not be. So there are some actual reasons for making a graph.

A demonstration of key points of the required practical to investigate the effect of varying force or mass on the acceleration of an object for GCSE physics and combined science.

Newton’s Second Law of Motion states, “The force acting on an object is equal to the mass of that object times its acceleration.” ...

Learn the uses of equations and graphs of motion and how to determine other aspects of the motion of objects. BBC Bitesize Scotland Higher Physics revision.