Youngsters' basic learning skills have plummeted in five years, with few children able to recite a nursery rhyme, Welsh head teachers have said.
Parents need to encourage children to read and play
About 60% of head teachers questioned said few children could recite a nursery rhyme when they started school.
And they said less than half of five-year-olds started school with basic talking and listening skills.
A similar number can recite numbers in order and just one in five can write their own name.
The views were revealed in a Basic Skills Agency report on Monday.
The agency urged parents to regularly read and talk with their children - or risk them falling behind when they start at primary school.
Seven hundred and sixteen head teachers in Wales gave their perceptions of children's skills when they start school.
Most reported a fall in standards of basic skills like talking voluntarily to others, talking about personal experiences, recognising their own names and counting to five.
How to improve skills
Talking, listening and responding to children
Singing nursery rhymes
Play with other children
Two thirds said fewer children could speak audibly and be understood.
Sixty-one percent felt few youngsters could recite rhymes or songs.
Over half of teachers said few children were able to listen and respond to instructions.
Children starting at Welsh-medium schools are better at early reading, writing and counting activities - 42% can write their name against 22% of pupils elsewhere.
Teachers said it was "absolutely essential" that parents talked and played with their babies and young children before reaching school.
"We need more opportunities for parents to learn how to help develop these crucial early skills," said Basic Skills Agency director Alan Wells.
"We need greater awareness of how important these early language skills are.
"The number of children starting school with poor speaking and listening skills should cause us all to worry and the numbers are going up."