Khan Academy — free lessons across school and adult learning

Khan Academy provides entirely free, self-paced lessons and practice in maths, science, computing, economics and more; resources suit primary, secondary and adult learners. Content includes video tutorials, practice exercises and personalised learning dashboards; it is available worldwide and free to use without payment. UK learners can sign up for a free account at https://www.khanacademy.org to track progress, access resources and use teacher/class features if relevant.