These activities can help you get better at adding and subtracting 1,000.
Adding 1,000
http://www.snappymaths.com/addsub/addsubp10/interactive/adding1000int/adding1000int.htm
Subtracting 1,000
http://www.snappymaths.com/addsub/addsubp10/interactive/sub1000int/sub1000int.htm
Adding and subtracting 1,000
http://www.snappymaths.com/addsub/addsubp10/interactive/addsub1000int/addsub1000int.htm