Learning the Full Maths Curriculum
The best website I've found for learning the maths curriculum is khanacademy.org.
This has several things that make it unique, the first being that children and parents can monitor their progress throughout the whole maths curriculum and that it remembers which subjects you've mastered, which are still to do and which you need extra practise at.
This immediately makes the whole process more flowing and fits each subject into the overall scope of maths.
The second thing is that each question has hints and a video to go with it, so you can either get stuck in and answer the question if you already know how (or can have a good guess), or there's help on hand when you need it.
Finally the overall dashboard, scoring system, way it chooses the best questions for you, etc. is awesome. Very easy to use, with a presentation somewhere between a game and a social media website, it's a really unique site that allows children to learn the whole maths curriculum from the basics to 8th grade, or with a 'learn everything' option which is the default.
Key Stage 2 Maths Games (Ages 7 to 11)
The BBC website has a selection of interactive online maths games aimed at 7 to 11 year olds teaching children about decimals, fractions, shapes and how to handle data.
Follows the national curriculum.
A selection of more typical arcade type games that cleverly incorporate algebra, multiplication, fractions and angles.
Fun interactive maths exercises, make sure you click the right grade:
Age 6-7 is Grade 1