To stay strong, patients should do some strength training at least twice a week. However arthritic pain can limit walking and activity. The wait for knee surgery can be long, which can lead to loss of muscle strength. Patients who need a new knee joint tend to be older. If older people do not exercise and become weak, they tire easily, and may take longer to recover after surgery. Patients recover faster after having a new knee joint if their leg muscles are strong. This is why exercise before surgery can help people to make the most of their new joint. Patients come to a joint school where the investigators show them exercises and advise how to get ready for surgery. Patients are given a sheet of pictures and prompts for each exercise but the investigators know that some people don't do the exercises that they are given. Exercises are more likely to be done if they are fun, if people can see they make a difference, if they know what to do, and if their physiotherapist can check what they are doing.