It has long been a rite of passage for young children; the moment they first begin to grasp how to tell the time as their parents patiently explain the significance of the “big hand” and the “little hand”.

But the ubiquity of mobile phones and tablets, with their digital 24-hour clock, is threatening to make the art of telling the time from a traditional timepiece redundant.

So much so that a school in Scotland has found that pupils as old as 13 are unable to tell the time from the ‘analogue’ clocks hanging in classrooms and corridors.

Teachers at Kilgraston School in Perthshire began to notice that more and more of its senior pupils had no concept of how to read a clock, or at best struggled to do so.

The problem had become so acute that it had even begun to threaten the girls’ exam prospects.

Dorothy MacGinty, head of Kilgraston, said: “Pupils sit in examination rooms with analogue clocks and we have found some who struggle to understand how much longer they have left for an exam because they cannot read the clock face.”

Now the school, in the town of Bridge of Earn, has begun to teach pupils to read a clock the old fashioned way, without resorting to their mobile phones.