Schools which celebrate St David's Day could be innocently reinforcing stereotypes of the Welsh globally.
Liz Thomas, formal sector officer for Cyfanfyd, an organisation promoting education for global citizenship in schools, said many cultural days often give false impressions of a country.
And she said Wales's March 1 celebration of its patron saint was no exception, as it misrepresented the modern-day Wales, which has moved on from coal mines and traditional dress.
She added that fair trade events, now celebrated by a lot of schools, might not really be so ethical.
"If we are talking about a celebration of Africa, why include tribal men beating drums?" she said. "Africa has moved on from then and we should be looking at countries as they are today."
Speaking at a special conference organised by Cyfanfyd to address race equality earlier this month, Ms Thomas told school representatives that education for sustainable development global citizenship (ESDGC), now a compulsory part of the personal and social education curriculum, had to go further to address prejudice and discrimination in society.
She later told TES Cymru that both cultural days and global weeks did not show the bigger picture. And she claimed she still encountered resistance from "white-only schools" which did not feel it was necessary to promote multi-cultural events.
However, good practice in schools across WalesJhas already been indentified. In Bedwas high Jin Caerphilly, every subject is linked to an aspect of ESDGC, even music, whereJpupils express themselves through protest songs and learning about Africa.
Last July, Estyn reported that only one in 10 schools and colleges is committed to teaching ESDGC. Inspectors found that many schools were not clear about identifying how and where they could develop the associated skills and values.
Susan Lewis, chief inspector, said experts needed to come up with a snappier name and a clearer definition of ESDGC to help teachers.
Teacher-training providers across Wales are now ensuring it is embedded in all their courses. But Ms Thomas admits that the issues they are dealing with are not easy for teachers to keep up with.
"What was thought of as good, fair trade practice a couple of years ago is not now," she said.
"Now it is being discovered that there is always a white middleman profiting -it is difficult."
A new ESDGC strategy, devised at the end of 2006, said there was too much inconsistency in the way it was taught in schools. Good practice was often down to visionary heads or individual teachers.
It claimed the subject went beyond recycling, a healthy snack shop or an international pen-pal scheme.
Comment cymru, page 27