Complex sentence: In 2001 fewer than 40 sixth formers attended the school but in 2008 the numbers had reached over 150 partly in response to courses offered by the school students have five one-hour lessons per week for each course that they do.
Split into simpler sentences: In 2001 fewer than 40 sixth formers attended the school but in 2008 the numbers had reached over 150; partly in response to courses offered by the school. Students have five one-hour lessons per week for each course that they do.