New Delhi:Badminton coach Pullela Gopichand is an example of an "excellent teacher", Prime Minister Narendra Modi said on Sunday. "I salute Gopichand's hard work and dedication towards the games," Modi said in his 23rd 'Mann Ki Baat' radio address. Indian badminton player P.V. Sindhu won the silver medal at the Rio Olympic games under Gopichand's coaching. Modi said teachers were as important as mothers. "For me, September 5 is not only Teachers Day but a day of learning as well. Teachers are as important as mothers in our lives. They spend their lives caring for their students," he said. Modi paid tribute to late Sarvapalli Radhakrishnan, the former President of India whose birthday is celebrated as Teachers Day. "He used to love to be known as a teacher. He lived the incredible life like a teacher despite being a President." Modi said he was still in touch with a man, now 90 years of age, who taught him years ago. His teacher writes to him with his own hand, said the Prime Minister. "He analyses whatever work I do in a month. He still tells me new things from various books that he reads. It is like he gives me a correspondence class every month," Modi said. Modi said he has "immense respect" for people with good handwriting as his own handwriting was not that good.