Making young children do worksheets instead of playing could stifle their creativity, says last year's Education Department early childhood teacher of the year.
Paula Wiley, who teaches kindergarten at Bannister Creek primary school in Lynwood, said play allowed children to communicate, problem-solve and think creatively.
"If we have children all doing the same worksheet at the same time, we're losing our creative thinkers of the world," she said.
"Yes, we know they can rhyme and circle the picture which starts with the same sound, but we won't allow them to think creatively."
Ms Wiley said many teachers were feeling pressure to use more formal ways of teaching, but it was up to them to be advocates for young children.
"The fear is that everyone's so worried about evidence that they want a piece of paper at the end to show this child can do this, whereas you can have evidence in lots of other ways."
Ms Wiley said even though she allocated a big part of her pupils' day to play, it was never random. She arrives at 7am every day to set up play activities to support the concepts being taught.
WA Primary Principals Association president Stephen Breen said some schools under pressure to improve results might have swung too far away from play-based learning.