Why do electrons flow in the opposite direction to current? I'm 15 and just had a question about physics and electric fields.
I've read that electrons flow in the opposite direction to current. Isn't current the flow of negative charge and  therefore the flow of electrons?
Or are they referring to conventional current?
 A: By 'current' we normally mean electrical (also called conventional) current, i.e. the amount of electrical charge that is passing a given point in the circuit at any given time.
If a positive charge carrier (say, a 'hole' in a semiconductor) passes from left to right, then that counts the charge $q$ to the current, over the time $\Delta t$ that the process takes.
On the other hand, if a negative charge carrier (most often, an electron) passes from left to right, that means that the total charge on the right is becoming more negative and the total charge on the left is becoming less negative, i.e., it means that electrical charge is moving from right to left. Thus, the electrical current goes from right to left, oppositely to the velocity of the electron.
A: We can safely say, that you are talking about electric current. It is defined as the "electric charge, which flows trough some point or region in given amount of time" (by Wikipedia):
$$
\textbf{I}=\frac{de}{dt}\hat{a}
$$
Bear in mind, that differential $d$ mrans small change, eg. small amount of charge divided by time needed for it to pass (which is also small). For understanding you can write as $I=\frac{e}{t}\hat{a}$.  $\hat{a}$ is unit vector. This is an arrow according to which you determine direction, and number line. Let's say, that it points towards positive numbers.
We can express current as with upper equation. We divide the amount of charge which was moved in the direction into which $\hat{a}$ points in time needed for this. This equation and explanation is valid even if you don't know anything about electrons in material.
So in metals (or other conductors, where main carriers of charge are electrons) the change of charge $de$ is negative. When their velocity points in the direction of $\hat{a}$ (eg. is positive), the direction of current $\textbf{I}$ is negative, because of negative $de$. So you can se, that you have positive direction of travel for electrons, and negative direction of charge, which means, that they are exactly opposite. You could also say, that direction of velocity is negative, and current will than become positive, which will also lead us to opposite direction.
A: Looking from a layman perspective:
A flow/current is created only when there is a potential difference. By definition/convention a flow or current always flows from high potential to low potential. E.g. Water flows downwards, air flows from high pressure area to low pressure area and likewise.
In electrical world, this translates to positive (high) and negative (low) voltage. Like other examples mentioned above, electrical current will flow only when there is a potential difference.
Coming on to the flow of electron, by their very nature, the electron will tend to flow towards the +ve side because they have -ve charge, and hence they flow opposite to the conventional direction of current flow (from +ve to -ve).
