Complex sentence: On 3 November 1989, a boy celebrated his 16th birthday at a Stockton surf club with minimum supervision, during which 14-year-old Leigh Leigh had sex on the beach with a boy aged 15.
Split into simpler sentences: On 3 November 1989, a boy celebrated his 16th birthday at a Stockton surf club with minimum supervision. Shortly afterwards Leigh had sex on the beach with a boy aged 15.