Math:

Addition:

2nd Grade:
http://www.beaconlearningcenter.com/
Click on Circus Fun
http://www.aaastudy.com/add.htm
Click on Addition

3rd Grade:
http://www.bbc.co.uk/schools/ks2bitesize/maths/number.shtml
Click on Addition

3rd and 4th Grade:
http://www.bbc.co.uk/schools/ks2bitesize/maths/number.shtml
Click on Multiplication