Online music-teaching plus a la carte digital sheet-music sales makes for an interesting recipe. That’s what’s on offer with Playground Sessions, a US-based startup boasting Quincy Jones as an investor and adviser. The service focuses on teaching people to play the piano through lessons delivered over the internet, with instructional videos and digital sheet music for around 90 songs – including works by Beyoncé, The Jackson 5, Ray Charles and Aerosmith. The business model will be lucrative if Playground Sessions takes off: people pay $9.99 a month for membership – including a ‘bootcamp curriculum’ and ongoing support, progress-tracking and social features – but pay extra for the a la carte sheet-music – $3.99 a pop or $5.99 if it comes with a video. Non-members can simply buy these, but pay more: $7.99 for sheet music and $14.99 for video tutorials. Either way, people also need their own MIDI keyboard to plug in to their computer.