Have you ever sung “A‑B‑C‑D…” in preschool and realised it sounds oddly familiar?
It was as if somehow you knew the song about letters before you knew about letters!
Could it be that the “alphabet song”, which is usually taught to children when they are beginning to learn how to read, is similar to “Twinkle, Twinkle, Little Star”, a popular lullaby and other nursery rhymes that are often sung to infants?
VERDICT:

TRUE
Yes, the familiar tune of the Alphabet Song is the same melody used in “Twinkle, Twinkle Little Star” and in other nursery rhymes such as “Baa Baa Black Sheep”.
The anonymous melody dates back at least to the 1740s and probably originated in France.
Many people think Mozart wrote the melody, but he merely popularised it by writing variations on the 18th-century French folk song “Ah! vous dirai-je, maman”, which is the first published example of setting lyrics to that melody.
In the 19th-century, the same melody was repurposed for the English lullaby “Twinkle, Twinkle, Little Star” and the American song “The Alphabet Song”.
It’s also essentially the same melody you hear in the nursery rhyme “Baa Baa Black Sheep”!
That melody has endured for centuries because it’s simple, catchy and easy for children to learn, making it perfect for everything from teaching letters to soothing lullabies.
References:
https://medium.com/@westwise/where-did-the-abc-song-come-from-dfc18b2ed
https://www.britannica.com/story/did-mozart-write-twinkle-twinkle-little-star
