I'm part of a small team working to build an interactive app that helps people train/practice and learn about music theory. The app is currently free and genuinely needs the input of musicians and people interested in music to ensure that we are doing work that people will find useful. As we are still building and constantly making updates and changes, feedback and opinions from potential users is extremely beneficial to us. If you are interested in checking it out and helping to shape something you could see yourself using in the future, or you would just like to offer feedback regardless, you can find the link below! Thanks so much - Hayley.