The Natural Minor Scale has pitches that are the same as its relative major key but the ordering of the whole tones and semitones is different. The organization of whole tones and semitones in an ascending natural minor scale are in the following order:

Practice singing the natural minor scale using a strategy of your choice.  Three strategies are provided below. The Movable Do solfege system uses the singing syllables starting on La (the sixth scale degree of the relative major scale), the scale degree system uses numbers and the fixed Do solfege system has the first scale degree considered as Do.   

Practice singing the natural minor scale in different keys using the system of your choice.