Electric current is the flow of _ through a substance.

Electrons

Explanation:

A current is a flow of electrons for this to happen there must be a closed circuit.

- The electricity is nothing but a flow of free electrons present in the external surface of the electricity conducting substance.

The flow direction of this electron flow is also the direction of electricity flow.

- There is a type of electrical circuit which is known as the closed circuit. This circuit is completely connected with the two terminals of the battery and there are no hindrances in the path of electricity flow in these circuits. That's why current can only flow through these complete circuits.

fumikage isn't really a bird, and tsuyu does have teeth. tsuyu has a transformation quirk which still allows her to be partially human. otherwise we'd have a large frog running around. fumikage has teeth because again, he isn't a bird. his head was a quirk mixture if i'm correct.