One of the great advantages of a digital piano over an acoustic piano is the extra features that will enhance learning and make playing more fun.
Additional sounds encourage creativity and practicing. For example, a student can play their Bach invention with the sound of a harpsichord, or their jazz prelude on some cool vibes. With sounds such as strings, brass, organs, guitars, drums and many others, there are endless possibilities for exploration.
Timing is essential to playing the piano well and a metronome will help develop your rhythmic and timekeeping skills. Most digital pianos will have a metronome built in that will allow you to select from a variety of different meters with a choice of different voices - even a dog bark to encourage young students. They also mean you have one less item to purchase.
Twin piano mode
Some digital pianos have a feature called twin piano mode which splits the keyboard into two identical key ranges, allowing two performers or a student and teacher to play side by side in the same register. With models that support the connection of two separate sets of headphones, players on the left and right sides can listen and play together in pair mode, or completely independently using individual mode - useful if you have two children learning the same piece.
Recording your performance helps analyse exactly what's going on in your playing. The record features on digital pianos allow you to play back and pick out any timing or melody problems, nipping bad habits in the bud before they become ingrained.
Finally, some digital piano manufacturers provide free apps that can help liven up practise and motivate kids to play. Apps for sight-reading skills ask the pianist to identify written notes, flashcard-style apps help with understanding music theory, while aural training apps develop abilities such as listening for particular scales or intervals. There are even apps that let users play along to favourite songs in their iPhone or iPad wirelessly through the piano's sound system.