The performer in the above video is one of my students, Mounisha on flute, 15 May 2018.
I like the way she has tastefully co-ordinated the color of her flute so that it matches her school uniform.
Mounisha turned 11 that year, I believe.
This arrangement of Old MacDonald Had a Farm is written in the Key of B Flat.
It’s not very hard, but will give you strong feeling of achievement, as it is so well-known.