Education Secretary Michael Gove said the changes to the national curriculum would help children of all abilities to succeed as "children actually enjoy being set a challenge".
Mr Gove told Daybreak: "I think the most important thing is to make sure that we understand when children arrive in school how well they're performing so that we can then ensure that those children who are bright are really stretched.
"But also those children who may arrive at school not perhaps with all the preparations in place for them to enjoy their learning are helped to enjoy their learning so that children of all abilities can succeed.
"One of the things I've found is that children actually enjoy being set a challenge, and as soon as you ensure that you understand the level at which children are working, then you are able to set an appropriate challenge.
"All of us thrive when we are set a challenge that's just a wee bit beyond what we're comfortable with, but within our grasp".