Just thought I'd share a site we've been using for about 1 1/2 years.  ixl.com

What we like about it: 

• Can view and practice based on STATE STANDARDS for each grade!
• Free 20 questions per day (what is great about this is that the child/student does not get overwhelmed)
• Good feedback and explanations for improvement

We've recently taken a year's subscription so we can practice unlimited and maintain reports on progress/mastery.  I like that the site encourages additional practice and challeges the student as they go on in a specific area (but I must admit my child is not thrilled; when 1 question is missed, it takes 5-10 additional questions to reach mastery...not a punishment, simply making sure the student gets enough additional practice after explaining how to solve/answer).

It's a great way to break up the monotany of worksheets.

For any child under 10, the 20 questions a day is plenty...though I'm glad to have the reports.  For children 10-13, 40 questions a day without angst.  We have tried just mastering one area a day, but the pressure to reach 100% can add undo stress.  Encourage a break around 85%.  And try switching to another area, leaving them partially done so the child can go back and finish when motivated (for the award sheet, which I admit is mediocre).

Hope that helps (we are not affliated in any way with the site, just finding it useful)  Blessings

Wow, that is a great website.  Thanks for the info!

it has chalkboard examples... my kids use this when they get hung up on something... it goes through Algebra, Calculus, Trig as well.