Complex sentence: Kelly hears the talk about closure and tells the rest of the school, they then make a plan to save the school which involves getting to the final of "School Challenge" and stealing the painting'the girl with a pearl earring'.
Split into simpler sentences: Kelly hears the talk about closure and tells the rest of the school. They then make a plan to save the school, which involves getting to the final of "School Challenge" and stealing the painting'the girl with a pearl earring'.