Scuse my ignorance here, but surely the age is irrelevant - children in first grade in the US will cover roughly the same level of work as children in primary 1 in the UK. But, it is difficult to compare - school sylabuses will be different between England and Scotland never mind between here and the US. IMO the education system here is better than the US, so you may need to go up a grade or two to get appropriate work. If you need extra worksheets, I would ask their teachers or use the books you buy here for extra maths, english, writing, spelling etc. they are usually pretty clear in the appropriate age range and generally only cost a pound or so from the supermarket