The Foundation Phase is a vital part of developing young children's skills in speaking, reading and writing in Welsh.
We have found that the rate at which children acquire Welsh language skills is affected by whether or not children are learning alongside others who share similar backgrounds in home language.
Our report shows that in classes with mixed linguistic backgrounds, children from non-Welsh speaking homes sometimes progress too slowly and the progress of pupils from Welsh-speaking homes can be hindered.
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Carl Edwards has the latest edition of Newsweek Wales
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