They about have to be in junior high or high school. Their school has a newspaper run by students without adult supervision.

@FloydPinkerton Because they are rather young ponies. Roughly equivalent to pubescent years. Maybe not quite elementary school, but not much farther than middle school.

Who says they’re in elementary school?

@B2C  
I figured it was meant to be a dot product of ∇ and D.

It explains the magic needed to keep the Sun and the Moon revolving around the planet. Even if they do not fully understand it, it is important that little fillies already learn about this stuff in elementary.

My guess is it has something to do with unicorn magic, considering it is seen at the magic school, and Cherilee does have unicorns in her class.
 
@Urist The middle symbol on the right of the equals sign kind of looks like a comma. So maybe the equation somehow generates an ordered pair?

Vector calculus IS a little advanced for elementary school fillies and colts. As for what it means, the equation looks to be related to electromagnetics, although in that case part of it is wrong and it doesn’t seem to mean anything anyways.  
Based on the assumption that it is related to electromagnetics, Here’s what I’ve been able to figure:  
The numerator (top portion) of the first part of the left side of the equation is the gradient (∇, the nabla symbol, represents the vector differential operator, del) of the electric displacement (vector) field, D. This is where the error is, a gradient can only be taken of a scalar field, not a vector field.  
The denominator (bottom portion) of the first part of the left side of the equation is the complex conjugate of the electric permittivity, ε, times the magnetic permeability, µ. This doesn’t seem to mean anything since there are no imaginary numbers involved with either value. However, ε multiplied by µ can be used to find the phase velocity of electromagnetic radiation through a particular medium.  
The second portion of the left side of the equation is delta, Δ (usually denotes the change of a quantity, although one isn’t specified in the equation), added to that side of the equation. Without knowing what is changing, this doesn’t mean anything.  
What the equation is intended to be set equal to is a mystery, I can’t tell what symbols those are supposed to be or if they were intended to be actual symbols in the first place.  
The drawing of what appears to be a planet with a ring is probably unrelated and if the second “equation” is even an equation, it isn’t complete. Its just 12 minus something that I can’t make out.
 
TL;DR, chances are the equation is nonsense.

“Remember kids, if this weren’t a magical fantasy land, you’d have to learn stuff like this!”

I’m with the owl. I could never just lick one. I always ended up biting one.

*458

@Feral
 
The world may never know.

@Feral
 
It took me 858 licks.
 
*Results may vary.

E = MC Hammer

It’s the equation that explains how many licks it takes to get to the tootsie center of a tootsie pop.

well there is also a “12” there and something resembling a halffilled circle.

V this

It’s an equation to determine whether or not Doritos are food. The answer is “Kind of”

my head cannon was always that, their sun (which is magical and smaller than a real one) rotates magically around their planet and this is some kind of poorly remembered equation for the radius of their “sun”.

Toon Physics 101.

Oh come on it’s only… backwards Delta multiplied by D over Epsilon multiplied by Upsilon?  
…  
Yeah…

I’m guessing they have some unique math symbols to describe certain equations.
 
I’m going with Gittons’s theory, and that it has something to do with gravity manipulation and how the Princesses are able to control the heavens.

Ponies have a higher education than us.

Equestria’s planet doesn’t spin, silly.