Acceleration is the slope of a velocity vs. time graph.

Here's why:

* Acceleration is the rate of change of velocity over time.

* Slope is a measure of how steep a line is, which represents the rate of change between two variables.

So, if you plot velocity on the y-axis and time on the x-axis, the slope of the line connecting two points on the graph will represent the acceleration during that time interval.

Here's a simple way to think about it:

* Steeper slope: A steeper slope means a larger change in velocity over a shorter period of time, indicating greater acceleration.

* Shallower slope: A shallower slope means a smaller change in velocity over a longer period of time, indicating smaller acceleration.

* Horizontal line: A horizontal line has zero slope, meaning no change in velocity and therefore zero acceleration.

Let me know if you'd like to explore specific examples or applications of this concept!