http://www.mathsrevision.com This website can be used for all levels in BGE as well as Senior Phase. Just look for your level on the diagram and click on it to see all of the additional notes and work!
http://www.sqa.org.uk/pastpapers/findpastpaper.htm?subject=Mathematics Perfect for finding recent National 5 and Higher Past Papers along with their marking schemes. Try and give yourself the same amount of time as in the actual exam, and use the marking scheme to score yourself!
http://scholar.hw.ac.uk/ Pupils will have their own usernames and passwords for this resource. Unfortunately, we cannot access this information for you if you have forgotten. You will need to see your tutor teacher for this information.
https://www.highermathematics.co.uk/higher-maths-whole-course/ A fantastic website for Higher pupils, includes all recent and Old Higher past papers, along with homework exercises and revision notes.
https://www.national5maths.co.uk/free-national-5-maths-2/ A similar website to above except for pupils studying National 5 Maths.