This is the heart-warming moment a schoolgirl tumbled over while she struggled to carry a heavy backpack stuffed with a surprise gift for her mother - before a kind passer-by helped her.

The exhausted youngster Aina Sota, 7, filled her rucksack with the 36 milk boxes - all free snacks she received from school - that she wanted to surprise her mum with but she had a hard time carrying them home during the 32c heat in Satun province, southern Thailand on January 25.

She had to stop and take a rest while walking home but when she tried standing up, the girl fell backwards because of her heavy baggage. She then struggled to get back to her feet.

Video footage from a passing driver, who pulled over when he saw youngster, shows the girl doing her best to wear the heavy bag while sitting down. However, she ended up falling over she then appeared to have given up and carried the bag in her right hand while her left hand held her lunch pack.

Soon after, a kind onlooker from the same vehicle approached her to help steady the bag on the first-grader's back. She then adorably continued her journey home.

The girl's mother Suchada Hadwang said: 'I normally pick my daughter up from school but she disappeared that day. I was surprised to find out that she walked home and carried the 36 milk boxes on her own.

'There are usually only four textbooks inside her but she took a lot of free milk from school so her bag was heavy because of that.

'She knows I like drinking milk so she wanted to bring lots home for us to drink together. She's so sweet.'

The girl was later able to reach home while dragging the bag and her boxes of milk, which she gave to her mother.