New Delhi, Sep 5 (IANS): "You should play and sweat a lot, at least four times a day. Promise you will do it," was the exhortation by Prime Minister Narendra Modi to children across the nation.

The prime minister, in a first such address to millions of students and teachers across the nation on Teachers' Day, also exhorted students to read biographies of people and books on subjects they like.

"How many are there who sweat a lot at least four times a day in play," Modi asked the students gathered in Maneckshaw Auditorium here, with the event being telecast to all schools in the country and live streamed.

"Till there is no play, there is no growth," he said.

He asked the students - "How many of you play a lot and sweat four times a day?"

When most smiled and laughed saying they did not play so much, the prime minister said: "At least four times a day you should sweat a lot, promise you will do it."

To which, the students responded with a loud "Yes".

He also asked the students to read biographies, saying it would take them close to history.

"Please read biographies, then we will reach near to history. You can read different biographies" of people in sports, trade, films, science, he said.

"This should be our endeavour. We get information nowadays, and not gyan (knowledge)," the prime minister said.