A terrified schoolboy started crying while looking for his 'lost' Covid-19 face mask - which has hanging on his chin all along.

Teacher Mew Kannikar was doing a class activity in Nakhon Phanom, Thailand when one of her students walked over to her in tears on August 6.

The worried teacher thought that the five-year-old boy was not feeling well. She asked him what was wrong and he said he was scared because he couldn't find his face mask.

Mew said: "I thought something was hurting him because he was crying, but he told me he was looking for his favourite face mask."

Kannikar, realising what's happening, tried to calm the boy down who resorted to crying before teaching him an important life lesson.

She told the boy to look for the mask in his bag and after a few minutes of pointless search, she asked him to look in the mirror.

The boy's face lit up after seeing that the mask had been under his chin all along.

The teacher added: ''Sometimes what we are looking for is right in front of us.''

Schools in Thailand reopened on July 1after months of home-based learning due to the Covid-19 coronavirus.

As part of strict hygiene rules, students are required to wear face coverings and practice safe distancing while at school.