There are many inter-house activities which take place at school.  Sporting activities are actually included in PE lessons on a half-termly basis and students can accrue points for their House just by taking part.  The school sporting calendar culminates in a whole-school Sports Day where Houses compete against each other for sporting success in a variety of activities.
However such Inter-House competitions are not just based upon sports, many other subject areas such as Drama and Music also hold such challenges.