There are several excellent math sites available that cover the Pre-Algebra, Algebra, and Geometry topics we study in Year 1 and Year 2. Many are interactive and give immediate feedback, including explanation when necessary.
This site is interactive. Students answer questions, receive feedback, and can choose another topic or continue practicing as needed. The eighth grade topics are the best options for Santan CATS students.
I recommend focusing on the "Beginning Algebra Topics" listed. The "Preliminary Topics" may also help reinforce basic skills. This site provides mini-lessons explaining the topics.
Algebra online is also a great resource. Each module has a tutorial powerpoint and practice page.
This site has instructional math videos on specific topics. It is a wonderful resource for both Algebra and Geometry.