Professor Andy Hargreaves also warned of a “possibility” the strategy of testing youngsters as part of efforts to close the attainment gap in schools may not be successful.
He told how Scotland was “at the front edge of the world” with efforts to ensure the large-scale testing of pupils does not bring “negative consequences” for pupils or teachers.
But he said there was a question over whether improvements in education standards brought about by such standardised assessments were “authentic”.
Pointing to schemes in both England and America, he said higher levels of achievement suggested by these had been “soundly denounced by the statistical societies of both countries as being statistically impossible”.
Prof Hargreaves, a member of the Government’s International Council of Education Advisers, was speaking as part of an inquiry by MSPs on Holyrood’s education committee into Scottish National Standardised Assessments (SNSA).
The assessments measure the progress of children in P1, P4, P7 and S3.
Ministers have faced repeated calls to ditch the system amid claims some P1 youngsters were left in tears by the “unnecessary and cruel” assessments.
Last year, Holyrood voted to halt the tests for the very youngest children, although this was not binding on the Government.
Prof Hargreaves, who works at Boston College in the US, told the committee: “I actually took the P1 test yesterday. Apparently I did quite well although I didn’t find all the questions easy.
“So I have some direct experience, at least as an adult, of what this looks like.”
While he said the plan for Scotland “initially was to have a high-stakes standardised test”, Prof Hargreaves said members of the International Council of Education Advisers had warned this “would have all kinds of negative impacts on teaching and learning”.
He said the testing format was “not at all high stakes”, although he said it was “at risk of becoming medium stakes”, which could result in schools coming under “undue pressure” to raise performance levels “over a relatively short period of time”.
He said: “Five years ago, systems around the world were in denial that large-scale standardised assessments have negative consequences for students’ learning and wellbeing, and also for the teaching profession responsible for them.
“I think that denial is disappearing very quickly everywhere and so we’re all starting to own the problem and say ‘how can we have large-scale information and also good support diagnostically, formatively, for teachers?’.
“The solution being tried here is different, which is to say how do we use large-scale assessments to inform teachers’ professional judgments so local authorities will have knowledge of their schools, but local authorities will not be able to compare with each other on the basis of the test results. It will be on the basis of the teachers’ professional judgment, part of which is informed by the test results.
“You are on the front edge here for the world. The world is really watching you.
“And figuring out how to make this a success over the next three years – given the possibility it may not be – and to be a learning government as much as an improving government is actually the key challenge, I think.”