One of my 13 year old pupils has become very enthusiastic about Raspberry Pi. She has bought her own RPi2 and has done basic GPIO bits and pieces, plus Sonic Pi and Minecraft Pi. She already has the books: "Adventures in Minecraft" and "Adventures in Raspberry Pi".
Her mum is looking for birthday gift ideas. Peripherals with coding instructions would be ideal. What do you suggest? Any particularly good books for moving on? Which peripherals would she get good use out of?
All ideas welcome. We're looking for something self-explanatory as there's nobody at home to help her.