Pupils are set homework by their class teachers. Teachers will set what is best for the pupils following their curriculum.
KS3 - pupils should be set homework once a week.
KS4 - English, Maths and Science set homework twice a week. All other subjects once a week.
Approximate lengths of homework:
Year 7 - 20 minutes per piece
Year 8 - 25 minutes per piece
Year 9 - 30 minutes per piece
Years 10 and 11 - 40 minutes per piece.