A helicopter is LIKE a hummingbird, it can hover
A helicopter is LIKE an aeroplane, it can fly forwards
A helicopter is LIKE a person on rollerskates on an ice rink, it is somewhat unstable
A helicopter is LIKE an egg with a straw stuck up its fundamental orifice
A helicopter is LIKE a lot of things, but it ain't a gyroscope. Some aspects are LIKE a gyro.
It gives the lowest common denominator (a student) a concept to work with. In the same manner, "Ground Effect is LIKE a cushion of air". The increase of RRPM as the blades cone upward is LIKE a skater spinning round and pulling their arms in. Teaching some students is LIKE practising bleeding.