Crucially, Trello boards lower the barrier to entry. A person who has never learned to read bass clef or understand time signatures can open a "Beginner" list, find a card for "Twinkle Twinkle Little Star," and follow the letter notes C C G G A A G . As they progress, they might move to cards that include rhythmic hints (e.g., [C] [C] [G] [G] for quarter notes) and eventually to cards that use a simplified alphanumeric notation (e.g., C4 for middle C). Trello’s drag-and-drop lists allow each learner to customize their own "learning path," moving songs from "To Learn" to "Mastered" with a simple gesture.