WHY MY DC MOTOR DIDNT WORK? It is a Question..

Why my simple DC motor did not work(rotate continuously)?
Can someone explain...
What is/ are the reason(s)?

Just testing my students knowledge on DC Motor.
Actually they did the practical by themselves, made a simple dc motor
BUT
most of their motor, coil didn't rotate continuously in one direction.

Видео WHY MY DC MOTOR DIDNT WORK? It is a Question.. канала Zamri 266