Modi, who is on a 2-day visit to Varanasi, first interacted with students of a primary school at Narur on the outskirts of the temple town and later met students of the Kashi Vidyapeeth and the children assisted by them at the Diesel Locomotive Works (DLW) campus.
"As students, it is vital to ask questions. Never feel afraid to ask questions. It is a key aspect of learning," Modi said in his interaction at the Narur school on a variety of subjects, calling the children "future of India".
A smile lit up the face of the school children when the prime minister said they must give importance to sports and must go out and play since it is essential.
"Students must give importance to sports. It is important to learn various skills, this will help you forever."
After the prime minister left the school, one of the students said, "Modi kaka told us 'khelogey to khilogey' (you will bloom only if you play).
"I came to your school on the special day of Vishwakarma jayanti. My greetings to everyone on this special day," he told the students.
Earlier, the students welcomed him enthusiastically saying "Swagatam PM." The school is aided by a non-profit organisation, 'Room to Read'.
The children also presented the prime minister greeting cards.
Senior BJP leader and local MLA Neelkanth Tewari said that as part of Modi's birthday celebrations 68 cakes weighing 68 kg each were cut at 68 locations in Varanasi.
Tewari, who is a UP minister, said, "Special prayers were being offered in 68 temples to pray for the long life of the PM. About a thousand earthen lamps have been lit at 90 locations."
Medical camps were held at 72 places, he added.
A cleanliness drive was launched on the streets leading to various ghats in the city, including the Ganga ghat and the Vishwanath Temple.
At Panini Kanya Vidyalaya, an 'yagna' (special worship) was conducted for the prime minister's long life.
Modi was elected to the Lok Sabha for the first time in 2014 from Varanasi and Vadodara, but chose to retain the former saying "Mujhe to maa ganga ne bulaya hai".
Earlier, on his arrival, the prime minister was received at the airport by Chief Minister Yogi Adityanath and state BJP president Mahendra Nath Pandey.
Anganwadi workers too were present to thank the prime minister for the slew of benefits announced by him for them recently.
After spending the night here, Modi will Tuesday inaugurate or lay the foundation stone of various development projects, cumulatively worth more than Rs 500 crore, according to a statement by the prime minister's office (PMO).
The event will be held at the amphitheatre of Banaras Hindu University (BHU).
Among the projects to be inaugurated by Modi are Integrated Power Development Scheme (IPDS) for Puraani Kashi and an Atal Incubation Centre at the BHU.
The projects for which the foundation stone will be laid include the Regional Ophthalmology Centre at the BHU. The prime minister will also address a gathering tomorrow, the statement said.