Simplify the following text for a Grade 12 native English-speaking person.
Original: In 1957 , John Bardeen , in collaboration with Leon Cooper and his doctoral student John Robert Schrieffer , proposed the standard theory of superconductivity known as the BCS theory ( named for their initials ) .
Simplified: Bardeen worked together with Leon Cooper and Robert Schrieffer created the standard theory of superconductivity known as the BCS theory , named after them .