When we talk about slope in calculus, we're really looking at something called derivatives. Let me break it down for you:

1. What is Slope?
   The slope of a line shows how steep it is. In calculus, we use this idea to find the slope of a curve at a certain point.

2. Derivatives as Slopes:
   A derivative of a function at a specific point tells us the slope of the line that just touches the curve at that point. If we have a function called $f(x)$, the derivative is written as $f'(x)$. It shows us how $f$ changes when $x$ changes.

3. Understanding Derivatives:
   When you calculate $f'(a)$, you are figuring out how steep the function is right at $x = a$. If the derivative is positive, it means the function is going up. If it's negative, the function is going down.

In short, derivatives help us understand how things change. Isn’t that cool?