Ds asked a reasonable question about decimals yesterday afternoon. So I explained how they worked in terms of tenths, hundredths, and thousandths etc and wanted to check his understanding so I asked him to convert some fractions to decimals.
He was ok with 0.1, 0.3, 0.9 etc but wrote 0.5 as 5/10 and 0.6 as 6/10. He didn't seem to have any grasp of simplifying fractions. So I explained, and wrote out a page of fractions for him to simplify and he understood it. So today I got him to change pairs of fractions to a common denominator, which he struggled with a bit. He got there in the end. I was a bit surprised school hadn't done that.
Then I got him adding fractions with different denominators. He found that hard too, which surprised me as maths is supposed to be one of his strong points and his teacher said he'd have no trouble with SATs.
When he went to bed he told me that he was glad I wasn't his teacher all the time as I made him work much harder than school. I was tutting to DH about school failing to teach him fractions when I decided to Google to see which year it's supposed to be taught.
Arggh. Adding fractions with different denominators is L6. I have put poor ds through fractions bootcamp over the last two days all for nothing. Poor lad is only in y2. 
. I did go into his room as he was still awake and apologise for being such a loon. Fortunately he found it quite funny and said he liked knowing hard stuff. ..