Complex sentence: Sports Day, the final house event of the year, was won by Chirol, however the house with the most housepoints (points received when students are extremely well behaved or do exceptional homework etc), was Kensington.
Split into simpler sentences: Sports Day, the final house event of the year, was won by Chirol. However the house with the most housepoints-points received when students are extremely well behaved or do exceptional homework etc-was Kensington.