David Cameron has been challenged by Parliament's only Green MP to answer a series of grammar questions for 11-year-olds during Prime Minister's Questions.

Mr Cameron insisted he was "absolutely delighted" his three children would face the controversial tests as he was put on the spot by Caroline Lucas.

Some parents have raised concerns that the Sats for primary school children were too prescriptive and risked putting them off reading.

Ms Lucas, MP for Brighton Pavilion, asked: "For the benefit of the House and for 10 and 11-year-olds up and down the country, will the Prime Minister explain what the past progressive tense is, will he differentiate between a subordinating conjunctive and a co-ordinating conjunctive, and finally will he set out his definition please of a modal verb?"

Mr Cameron responded: "Look, I have to say to her that the whole point of these changes is to make sure our children are better educated than we are. And that's why I'm delighted with three children at state schools going off to do these tests. I'm absolutely delighted they're going to be."

Schools minister Nick Gibb received a ticking off on Tuesday after he apparently failed to differentiate between a preposition and a subordinating conjunction while appearing on BBC Radio 4's World At One.