Although its possible to record and overdub parts on a computer via MIDI with all but the most basic portable keyboards, some models come with the facility for this built in. The simplest kind will capture only what is played on the keyboard in a single performance. This can be a useful practise aid in its own right, and it also allows the left hand to be recorded and then used to accompany the right (or vice versa) until the pupil is able to play both together. If more features are required, then multitrack recorders are available which allow you to record auto-accompaniment chord progressions and then overdub a melody and other parts for a more complete arrangement. You can even combine and edit existing MIDI Files with the auto-accompaniment and your own performances, and flagship products will often additionally feature audio recording, enabling you to add a vocal for instance.