"He is a kid on the sets. He converses with us in Bengali. If you present him with an idea, something of substance and importance, he will believe it," Sircar, who is shooting for the Big B starrer 'Piku' said.
The 'Madras Cafe' director, who is also a Bengali, said he is glad that Bachchan knows his mother-tongue.
During 1962-69, the actor had lived in Kolkata before shifting to Mumbai to join Bollywood. Since then he has worked with a number of Bengali film directors like Hrishikesh Mukherjee, Shakti Samanta and Rituparno Ghosh.
Even during the opening ceremony of the Kolkata International Film Festival recently, he had delivered his speech with an impressive smattering of Bengali.
For the Vidya Balan starrer Hindi film 'Kahaani', he had given his voice to the inspirational Tagore song 'Ekla Chalo Re' in Bengali.
Bachchan had launched the first look of Bengali film 'Open Tee Bioscope', which is co-produced by Sircar, last evening.