There are literally thousands of websites that should be helpful with any questions students may have. I have included some here but as I said there are many others. Google the topic you need help with, for example "linear equations" and you will find several results with written explanations and videos.
The school provides a paid subscription to ixl.com every student in my class has a login and password so they can practice skills we have learned.
www.khanacademy.org