Headmistress Kerry Robertson thought she was going mad when she met the new triplets in the nursery class - and each introduced himself as 'Isaac'.
But really, the Dunnottar Primary School boss was the victim of a trick by mischievous four-year-olds Josh, Jack and Isaac Senior.
The three youngsters, of Stonehaven, Aberdeenshire, are known for their pranks, which include covering their parents' bedroom with nappy cream and joke calling their father at work.
Mother Mandy, 43, says controlling the triplets, two of whom are identical, is hard work and the only way she can tell them apart is by colour co-ordinating them.
She said: "They have a colour each because when we were expecting them my husband and I were both quite worried how we would identify our new babies and we were worried that one that started off as Isaac would end up being someone else.
"We gave them each a colour - Jack is red, Isaac is blue and Josh is green - and kept their big toenails painted in those colours and that continued for one year.
"Jack and Isaac are identical so it can still be hard to tell them apart sometimes. Especially as Isaac has been known to try and put Jack's trousers on in the past with the idea of pretending that he was Jack and Jack was him."
It's not just pretending to be different people that gets the triplets into trouble, after a number of incidents such as redecorating their parent's bedroom with Sudocrem and prank calling father Dave, 40, from the house while he was at work.
Mrs Senior, who also has son Sam, eight, with Dave, said while they are always in trouble, the triplets look out for each other and make sure nobody is hurt.
Dunnottar Primary teacher Sally Nowak added: "They're certainly characters. They are quite full-on but are loving nursery and are very enthusiastic. They're all really happy little boys."