Differential of the first kind

Ok, kiddo, let's start with some basic math. Have you ever heard of something called a function? It's like a magic machine that can take a number and do something to it, like add, subtract, multiply or divide.

Now, imagine we have a function that tells us how fast something is changing at a particular moment. This is called the rate of change, and we can calculate it using something called a derivative.

The differential of the first kind is just another way of saying derivative. It's like a tool we use to figure out how much a function is changing at a given point.

Let's say we have a function that tells us how fast a car is driving at any given moment. We can use the differential of the first kind (a.k.a. the derivative) to figure out how fast the car is accelerating or decelerating.

So, the differential of the first kind is just a fancy way of saying we're finding the rate of change of a function. Does that make sense, little one?