There are a number of websites to assist students with their studies and revision.
Perhaps the best revision website we recommend is: www.studyit.org.nz This is a Ministry of Education developed website, so it is official. It is aimed at helping New Zealand students with their NCEA subjects. This website includes revision notes, key tips, practice questions and links to other helpful sites. It provides a forum to discuss issues with students and teachers, such as emailing questions to expert teachers. Most importantly it is free to use!
There are also other New Zealand educational websites, which are operated by private groups and as a result there is some free sample material but these websites do charge for students to access and use them.
Please remember that these websites are not substitutes for work at school, but rather are additional revision support to help improve student understanding and achievement.