Hi CrushedVelvet99
First off - it's quite usual to report NC Level results for SATs as whole levels. And as wobblypig explained NC Level 2 is expected. The fact that you are aware your DC is working to 1a means that they're a high NC Level 1, but the notional goal for Y2 is to achieve NC Level 2.
So first off - take a deep breath. It's a good thing to understand early on that your child is a little behind - and that's all it is. This could be due to age, ability, interest, maturity, etc... so be assured that time is on your side and does help in these situations.
My DD1 finished Y2 as NC Level 1 in maths and was completely unable to take 1 from 10. I did try to work with the school, but I had to raise our concerns about maths and the school chose to be very defensive and loath to recommend we do more at home.
My advice, from experience, is doing more at home does help. Maths is a way of thinking and it requires skills and therefore benefits from practice. However, we're now in an era where practice in maths doesn't necessarily have to be dry worksheets, rote reciting of number facts like times tables, etc....
First off there is a wealth of free websites out there that provide great practice at this level:
BBC Bitesize KS1: www.bbc.co.uk/bitesize/ks1/maths/ - this is a website for revision in preparation for KS1 SATs. You can adjust difficulty as well. (there also are English & Science bits for BBC Bitesize KS1 if you're interested).
Math Champs: www.mathschamps.co.uk/#home - free on-line games developed for age ranges 5- 7, 7 - 9 and 9 - 11.
Oxford Owl now has a maths site (in addition to their fantastic reading site): www.oxfordowl.co.uk/for-home/maths-owl/maths - if you click the fun activities tab - there are things by age group. (have an explore of other tabs as well).
I also highly recommend Woodlands Junior School Maths Zone: resources.woodlands-junior.kent.sch.uk/maths/ - under number skills there are useful links to games to help support addition/ subtraction/ work with 100 number square and place value.
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If you have a tablet/ smartphone/ ipad/ iphone:
PC Advisor recommends a number of math apps here: www.pcadvisor.co.uk/features/software/3380559/best-maths-apps-for-children/
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We ultimately went the route of an on-line tutorial. I have posted elsewhere as have others here on mumsnet about our success with various on-line maths tutorials:
komodo maths: komodomath.com/
mathletics: www.mathletics.co.uk/
maths whizz: www.whizz.com/
mathsfactor: www.themathsfactor.com/
mathsfactor was what we used, but as I said various parents have had great success with the others. In all cases they'll assess your child and start from where they're at. I also think that most offer a free trial - so you can see if the format works for your child (holds their interest, is the right pace, etc...).
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Finally, have a visit at a book shop/ large newsagent. There are tons of workbooks out there. Some are very formal (all numbers) other are more child friendly, lots of pictures and teaching through images as well as numbers. My advice if you go the workbook route is take your DC with you and let them help you chose the book. What interests them visually, is likely to also help them do maths.
My advice for you is this. BE POSITIVE. Even when you're struggling to believe they're going to crack it. Try to make it more of a game than a drudge. Little and often really does work.
There's so many ways to help with maths now and so much out there (much of it for free) that there really is help out there and solutions to any sticking point.
Remember December is very early in Y2, so achieving NC L2 by late Spring is still a possibility for your DC. Try not to panic about this though. My DC didn't achieve NC L2 at KS1 and she's a very solid NC L5 now (with the school determined to sit her for NC L6 paper in maths).
HTH