To figure out the Solfège to Twinkle Twinkle Little Star, I attempted to visualize the intervals between the notes and their Solfège syllables. Here is an explanation on how I tackled the song: Just by thinking about the song, I was fairly certain that the first note was the tonic, so that was easy. While I was singing the tonic, I thought ahead: I was fairly certain that the melody jumped up a fifth (to Sol), so I noted that that was the next note required to sing. Through the rest of the piece, while thinking ahead, I noticed that the melody was also scalar. That also made the figuring-out process easier — I just thought of going down the scale to identify the Solfège. Overall, identifying the leaps and steps in advance while singing made the Solfège easy to figure out.