Composed by John Lennon, at first he "hammers the melody on the same note." (The Italian composer Monteverdi discovered the effect of hammering on the same note. He called the style "stile concitato"). Then comes the middle part in long notes. The middle part has a change of keynote, which is unusual with such a change in a middle part. And then the rise in falsetto. Typical of Lennon's songs, there is also a rise of excitement. When you think that the mood will cool a little - when you come to the middle part - the excitement instead increases.
The Beatles performed this in their first movie, A Hard Day's Night. It was used in a scene where The Beatles sing it to a group of girls, one of which was played by an actress named Pattie Boyd. This was the first time George Harrison met her - he fell for her and married her a few years later. They divorced in 1977, and Pattie married Harrison's friend Eric Clapton in 1979. That marriage also ended in divorce, but along the way, Pattie inspired some of the most famous songs of all time, including The Beatles' "Something" and Clapton's "Layla."
This was done in three takes on Tuesday, February 25, 1964. But it didn't end there - they completely remade it the next day. The take you hear on record is Take 22.
John Lennon's vocal was double-tracked to make it stand out. This was released as the B-side of "A Hard Day's Night."
Lennon played the harmonica solo. McCartney played a 12-string electric guitar on this track.
At first, Lennon was proud of the composition, and said in 1964 that the song was one of the three best songs in the film A Hard Days Night. Later on he lost his self-confidence as a lyricist, and would often slag off his own songs as meaningless. He said in 1980 that "I Should Have Known Better" is, "just a song, it doesn't mean a damn thing."