1) Amendable 2) Corrigible 1) Can be made better 2) Corrigible 3) Susceptible of improvement 
• (a.) Capable of being used to advantage; profitable; serviceable; advantageous. • (a.) Capable of being improved; susceptible of improvement; admitting of being made better; capable of cultivation, or of being advanced in good qualities.
Im·prov'a·ble adjective [ From Improve .] 1. Capable of being improved; susceptible of improvement; admitting of being made better; capable of cultivation, or of being advanced in good qualities. « Man is accommodated with moral principles, improvable by the exercise of his...
[adj] - susceptible of improvement
improvable 1. Capable of being improved; susceptible to improvement. 2. Capable of being used to advantage; profitable; serviceable; advantageous.
adjective susceptible of improvement