Short run stages of the law of variable proportions
Stages 
Terms used 
TP 
AP 
MP 
Stage 1 
Increasing returns to the factor

Starts from origin, increases at an increasing rate and then increases at a diminishing rate 
Starts from the origin and then increases till its maximum point 
Increases, reaches a maximum and then starts falling 
Stage 2 
Diminishing returns to the factor 
Increases at a diminishing rate till it reaches the maximum point 
Falls continuously 
Falls continuously till it is equal to zero

Stage 3 
Negative returns to the factor 
Falls 
Falls continuously 
It is negative 