This website is a great math contest practice location. Our students are so over committed, they don't have time to practice as a group for a math team...I'm not sure they'll do this. I did have an extra advanced 8th grader working on it when he was finished with his homework. It lets you try a problem twice, shows a solution, and builds in difficulty. I have lots to learn from these problems -- many of which are beyond Core Curriculum.

We have participated in this contest for 3 years.  It doesn't cost anything except for the printing of the questions for each team and/or team member.  It is a group contest -- up to 6 per team.  Each team needs a computer that can only access the Purple Comet site during the 60-90 minutes of the exam.  Any preloaded software may be used to find a solution.  It isn't multiple choice, so guessing doesn't do much good.  I had 2 teams try that last year and didn't get any of the guessed problems correct.  Tough contest -- there are only a couple of Iowa high schools participating so far.

This is a site for math or TAG teachers.  The Alcumus section gives one problem at a time starting easy and building in difficulty.  You get 2 tries to get it right and then it shows you one or two correct methods of finding the solution.  The problems come from older national mathematics exams.

This is a free Computer Algebra System designed to go with the Core-Plus Mathematics Curriculum. We are using a different curriculum, but this was referenced as a free tool as an alternative to the leading calculator product. Since we will be 1:1, my students don't need to invest in those calculators. CAS is not allowed on any college testing as of yet.

I have been using this tool to develop/convert investigative activities for Geometry through Calculus. The files files can be exported to HTML in a nicer format that Geometer's Sketchpad 4.0. I haven't tried GSP 5.0.