Wales education "faces challenges", says Pisa chief
2 December 2013 Last updated at 14:16 GMT
Wales faces a "very significant challenge" if it is to move into the top 20 of the international education league table by 2015, according to the deputy director of the tables.
The results three years ago of the so-called Pisa tables saw Wales tumble down the rankings.
The latest results are due out on Tuesday.
Charlotte Dubenskij reports.