Teachers are unhappy at parents using video footage to challenge results of a primary school sports day.
Proud mums and dads have been filming races, jumping events and throwing contests while watching their children.
But some have brought video “evidence” into a school in Cardiff to dispute the results teachers on the finishing line announced.
The headteacher of Ysgol Mynydd Bychan in Cathays has sent a letter to parents warning them to stop the practice.
Parents have demanded official standings were changed based on their footage, but the school had refused to budge in the results row.
In a strongly worded letter, head Sian Evans has said: “Teacher’s word is final”.
The letter added: “The members of staff at the finish line, and nobody else, have the absolute final say and as to the first, second and third place positions.
“Unfortunately, during the last few years parents have approached members of staff with evidence that they had filmed on electronic devices such as iPads in order to prove that their child should have been awarded a higher position in a particular race and comments also appeared on Facebook.
“If this happens again, there is a strong possibility that we will have to consider changing the competitive nature of our sports morning.”
“The arrangements for the smooth running of the morning are very tight and take quite a bit of arranging. Members of staff work hard in various ways during the morning.”
The Welsh language school has 200 children and holds its sports day at the nearby National Indoor Athletics Centre on the Cardiff Met University campus.